Arafat faces internal crisis after his security forces kill three Palestinians

Yasser Arafat's security forces turned their guns on demonstrators in the Gaza Strip, killing at least three, including a 12-year-old boy, as the missiles fired at Afghanistan blew open the rift between the Palestinian authorities and "the street".

The spectacle of protesters being shot dead by their own police – as opposed to trigger-happy Israeli troops – caused an explosion of popular anger and precipitated Mr Arafat's most serious internal crisis for six years.

The unrest continued for hours, with gunfire echoing through the strip's overcrowded streets as darkness fell. Angry mobs destroyed police kiosks, overturned cars, set fires, smashed the windows of a Palestinian airline office, and trashed a police station in a Gaza City refugee camp. At least 50 people were injured, including some policemen.

University and schools in the Gaza Strip have now been closed by the Palestinian authorities in an attempt to stifle the unrest.

The scenes – which were precisely what the US and its allies had feared – began when the police attempted to stop thousands of students from Gaza's Islamic University, a Hamas stronghold, from taking a demonstration against the US-British attacks on Afghanistan into the streets outside their campus.

The police were under orders from the Palestinian Authority (PA) to clamp down on demonstrations, especially if they expressed support for Osama bin Laden.

A spokesman for the PA said that the student demonstration had not received an official permit to leave the campus. Palestinian security forces banned television cameramen from filming the protests, even detaining some, and later barred foreign correspondents from entering Gaza from Israel.

But some footage did escape the censorship. It showed protesters brandishing pictures of Mr bin Laden. Spectators said they saw posters reading: "Hamas supports bin Laden."

The media ban, crudely applied and self-defeating, was a reflection of the PA's desperate desire to distance itself from Mr bin Laden, for fear that the Palestinians will be accused of condoning the atrocities in America and branded as supporters of terrorism.

The atrocities have been strongly condemned by Mr Arafat and his officials, as well as the majority of Palestinians who, although highly critical of the United States' unwavering support for Israel, were horrified by the 11 September attack. But Israel has tried tirelessly to link the Palestinians with the outrages in America.

The PA's task was made harder by Mr bin Laden's comments on a videotape broadcast on Al-Jazeera, the Qatari satellite television channel on Sunday, in which he strongly linked his cause with the Palestinians'.

The Palestinian Information Minister, Yasser Abed Rabbo, said afterwards: "We don't want crimes committed in the name of Palestine."

Israel and the US have long pressed Mr Arafat to arrest Islamic militants, who are especially popular in the impoverished Gaza Strip, as a main condition of a ceasefire. But yesterday's blundering attempt to snuff out protest was the worst incident since May 1995, when the Palestinian police fired on a Hamas march in Gaza City, killing 15.

Before the intifada, Mr Arafat and the PA were widely seen in Gaza as corrupt and inept, and willing to sell out the national cause during the Oslo talks. Resentment abounded within Hamas – which surveys now show has about 20 per cent support in Gaza – and the smaller Islamic Jihad, especially after its members began to be thrown in jail.

The PA's reputation has improved during the intifada. But yesterday's shootings, and Mr Arafat's decision to support the US-led coalition, are certain to increase the opposition. So far, he has delayed releasing any official public statement on the missile strikes.

The dead included 12-year-old Abdullah Franji and Anwar Akal, a student aged 20. The circumstances of the shootings were unclear. Several Palestinian officials claimed that they were committed by unidentified masked men, and that the police had only been firing into the air. But witnesses said that the police fired into the demonstrators, who had been throwing stones.