A list of mass killings in the United States since January

The latest mass killing in the U.S. happened at a suburban Chicago home, where a couple, their two children and three dogs were found fatally shot on Sunday evening. Officers were asked to check on the family at their home in Romeoville, about 30 miles (48 kilometers) southwest of Chicago after one member did not show for work that morning and phone calls went unanswered, police said.

Police have said without elaborating that the suspect, who died Wednesday after a fiery crash in Oklahoma, had a relationship with the victims. Investigators believe they know the suspect's motive but have not disclosed it.

The shooting was the country's 35th mass killing this year, according to a database maintained by The Associated Press and USA Today in partnership with Northeastern University. A total of 171 people have died in those killings, which are defined as incidents in which four or more people have died within a 24-hour period, not including the killer — the same definition used by the FBI.

So far this year, the nation has witnessed the highest number on record of mass killings and deaths to this point in a single year. According to the database, there have been more than 560 mass killings since 2006, in which at least 2,900 people died and at least 2,000 were injured.

Here’s what happened in the other U.S. mass killings this year.

UNIONTOWN, OHIO: Aug. 24

Five members of a family, including three children, were found dead at a home in Uniontown, Ohio, by police officers performing a welfare check. Authorities say a husband and wife and their two daughters and son died from gunshot wounds and their deaths are being investigated as a domestic dispute that turned deadly. It’s unclear who fired the shots.

OKLAHOMA CITY: Aug. 16

Police in Oklahoma City said a 28-year-old man fatally shot three young children — ages 9, 5 and 2 — and his estranged wife before taking his own life. Officers visited the family home following a report of a domestic disturbance. Authorities described the couple as married but separated and said police had never been called to a domestic disturbance at the home before. They added that investigators have not yet determined a motive.

HAMPTON, GEORGIA: July 15

A 40-year-old man is accused of fatally shooting four people, all in their 60s, in a suburb south of Atlanta. Police said the man’s motive was not immediately clear. The killings set off a massive search that ended with a shootout that killed the man in another suburb about 15 miles (24 kilometers) away. The exchange of gunfire wounded a sheriff’s deputy and two police officers.

SHREVEPORT, LOUISIANA: July 4

Multiple males are believed to have exchanged gunfire at an annual Independence Day block party just before midnight, leaving at least four people dead and at least seven others injured, according to police. Suspects were not quickly identified, and arrests were not immediately made.

PHILADELPHIA: July 3

A 40-year-old man is accused of opening fire randomly with an AR-15-style rifle, killing four people and wounding four others, including a 2-year-old, in a southwest Philadelphia neighborhood. Authorities said the man fatally shot another person in a row house the day before.

GREEN POND, SOUTH CAROLINA: July 2

A 33-year-old man was charged with murder in the killings of his sister-in-law and 11-year-old daughter after authorities found six people dead and one person in critical condition at a home while responding to reports of a house fire and stabbings, officials said. They did not immediately identify a motive. The man was later charged in connection with the other four deaths, according to media reports.

KELLOGG, IDAHO: June 18

A 31-year-old man is accused of fatally shooting four members of a neighboring family in their apartment on Father's Day. The man was upset that the neighbor's 18-year-old son had reportedly exposed himself to the man’s children, a police document alleges.

SEQUATCHIE, TENNESSEE: June 15

A 48-year-old man is thought to be responsible for killing himself and five others — including three children and his estranged wife — in a home where police responded to a shooting and arrived to find the residence ablaze, authorities said. A seventh person suffered gunshot wounds and was found alive at the home after firefighters extinguished the flames.

MESA, ARIZONA: May 26

A 20-year-old man shot four men to death and wounded a woman in a 12-hour crime spree in metro Phoenix, authorities said. He told police that he met the victims at random that day at a range of places, including a park and a convenience store, and became angry when the subject of drugs came up.

NASH, TEXAS: May 23

Authorities jailed an 18-year-old man in connection with the shootings of his parents, sister and brother inside a home. A victim's co-worker who went to the home after one of the victims failed to show up for work told police that the man said “he had killed his family because they were cannibals, and they were going to eat him."

ALLEN, TEXAS: May 6

A 33-year-old man with an arsenal of legally-purchased firearms killed eight people and wounded seven others at a Dallas-area shopping center. He had posted online about his white supremacist and misogynistic views. A police officer fatally shot him within four minutes.

LAKE WALES, FLORIDA: May 2

A 38-year-old man was suspected of fatally shooting a woman and her three children after police were called to an apartment complex where they found the bodies. After an hourslong standoff at a motel, police fatally shot the man.

HENRYETTA, OKLAHOMA: May 1

A 39-year-old man fatally shot his wife, her three children and their two friends before killing himself, authorities said. They were all found dead on his rural property. He was a convicted rapist who had been freed from prison early, despite facing new sex charges in a separate case.

MOJAVE, CALIFORNIA: April 30

Four people were found fatally shot inside an RV in a remote Mojave Desert community, authorities said. There were no immediate arrests, but two people were being sought for questioning as “persons of interest.”

CLEVELAND, TEXAS: April 28

A 38-year-old man was arrested after a four-day manhunt. Authorities allege that the man charged into a neighbor's home and killed five people, including a 9-year-old boy, after his neighbors asked him to stop firing his AR-style rifle because a baby was trying to sleep.

BOWDOIN, MAINE: April 18

A 32-year-old man confessed to fatally shooting four people, including his parents, at a home. From there he fled and fired shots at moving vehicles on a highway. Several vehicles were hit by gunfire but the three people injured were a family all in the same car.

DADEVILLE, ALABAMA: April 15

Six suspects — ages 15 to 20 — were charged with reckless murder in connection with a shooting at a Sweet 16 birthday party that killed four people and injured at least 32 others. Two high school seniors were killed. The other two killed were 19 and 23.

LOUISVILLE, KENTUCKY: April 10

A 25-year-old bank employee armed with a rifle opened fire at his workplace, killing five people — including a close friend of Kentucky’s governor — while livestreaming the attack on Instagram, authorities said. Police arrived as shots were still being fired inside Old National Bank and killed the shooter during an exchange of gunfire.

MONROE, LOUISIANA: March 31

A 37-year-old man was arrested on arson and murder charges after a fire killed four people in a home, KNOE-TV reported.

NASHVILLE, TENNESSEE: March 27

A 28-year-old killed three children and three adults in a shooting at a small Christian elementary school before being killed by police. The shooter was a former student there. Police have said the shooter “was assigned female at birth” but used masculine pronouns on social media.

SUMTER, SOUTH CAROLINA: March 21

A 42-year-old former soldier shot and killed three children as they slept in their home while their mother frantically sought help, authorities said. He also killed an Army soldier who was at the home before killing himself. The shooter and the children's mother were divorced.

BIRMINGHAM, ALABAMA: March 13 to 14

A 28-year-old man was suspected of killing four people in overnight shootings. Authorities said the man approached a police officer and said he had shot two people in Birmingham and two people in St. Clair County.

DALLAS, TEXAS: March 12

An 18-year-old man and 20-year-old woman were charged in the fatal shootings of four people at an apartment. They told police they’d broken into the home to take money. The man admitted to shooting all of the victims. The woman had dated one of the victims, and they were involved in a custody dispute over their son. An infant was found unharmed at the scene.

MIAMI LAKES, FLORIDA: March 10

Police found three females and two males dead from apparent gunshot wounds inside a home, officials said. The wounds of one man appeared to be self-inflicted, leading investigators to believe the case was a murder-suicide.

COCOA, FLORIDA: March 1

A 36-year-old man was arrested after fatally shooting his teenage daughter, her mother and two other people, authorities said. Deputies responded after one of two surviving children had called a relative for help.

DAPHNE, ALABAMA: Feb. 22

A 21-year-old man was accused of killing his grandparents, his brother and a family friend with a handgun and pickaxe. Their bodies were found in the backyard of his grandparents' home and inside a bedroom in the house, police said.

ARKABUTLA, MISSISSIPPI: Feb. 17

A 52-year-old man shot and killed six people including his ex-wife and stepfather at multiple locations in a tiny rural community, authorities said. The man was armed with a shotgun and two handguns. A family friend said he had a history of mental illness. One victim was shot and killed while sitting in a pickup truck outside a convenience store.

LUTTRELL, TENNESSEE: Jan. 29

A 52-year-old man who complained of having “a devil in his head” fatally shot four children in his home before setting the residence ablaze and shooting himself, according to a prosecutor. The children were ages 5 to 15.

HALF MOON BAY, CALIFORNIA: Jan. 23

A 66-year-old man was charged with killing seven people in back-to-back shootings at two mushroom farms. He pleaded not guilty. Prosecutors said he opened fire at the mushroom farm where he worked, killing four co-workers and wounding another one. They said he then drove to a mushroom farm he was fired from in 2015 and fatally shot three former co-workers.

MONTEREY PARK, CALIFORNIA: Jan. 21

A 72-year-old man opened fire on a mostly elderly crowd at a Lunar New Year dance, killing 11 people and wounding nine. The man later died of an apparent self-inflicted gunshot wound. The massacre has been called the deadliest shooting in Los Angeles County history.

GOSHEN, CALIFORNIA: Jan. 16

Authorities announced more than two dozen arrests during a gang crackdown following the fatal shootings of six people — including a teenage mother and her baby — that investigators believe stemmed from a gang rivalry. Two men have pleaded not guilty to the murder charges.

CLEVELAND, OHIO: Jan. 13

A 41-year-old man was accused of fatally shooting his father, sister and nephew as well as another man and critically wounding an 8-year-old girl. The man pleaded not guilty. Police alleged that he shot victims in the head in different rooms of a home, then flagged down a police cruiser and directed officers to the scene.

HIGH POINT, NORTH CAROLINA: Jan. 7

A 45-year-old man fatally shot his wife and three children and then himself. Authorities said all five lived together in the home. Two others escaped the house. One of the survivors was a relative of the family and another was an acquaintance. Both were in their 20s.

ENOCH, UTAH: Jan. 4

A 42-year-old man fatally shot his five children, his mother-in-law and his wife and then killed himself two weeks after his wife filed for divorce. Child protective services had opened an investigation of the man on child abuse and threats to his family just weeks before the killing.