JERUSALEM — Six people were killed after Hamas-controlled police opened fire on a Fatah rally in Gaza City yesterday in some of the worst violence seen since the Islamist movement took control of the Gaza Strip five months ago.

While the Fatah leadership in Gaza was routed back in June, the movement was still able to mobilize tens of thousands for a rally to mark the third anniversary of the death of a Palestinian Arab leader, Yasser Arafat.

But there was always the risk that the sight of a yelling mob waving posters depicting the Fatah founder and shouting insults against Hamas would provoke the heavily armed members of Hamas’s “executive force,” who were recently renamed as police. At one point the crowd began to shout “Shia! Shia!” as an insult against Hamas, which enjoys strong links with the Shiite Islamic republic in Iran. Most Palestinian Arabs belong to the rival Sunni sect of Islam.

It is not clear if they were fired on first from inside the crowd, but it is known that six members of the crowd died and at least 130 were wounded, mostly from injuries suffered in the resulting stampede.

Groups of protesters and armed men were shown on Palestinian television running through the streets and police were seen beating a Fatah supporter with wooden batons.

The killings have sent relations between Fatah and Hamas to a new low, with the leader of the Fatah parliamentary bloc saying there would be no renewal of negotiations between the rivals.

“There will be no dialogue and no discussions with the killers and coup-makers of Hamas, no dialogue with those who do not believe in dialogue but only understand the language of blood and murder,” Azzam Ahmed said. “I am convinced the Palestinian people will purge them from their ranks and that the blood of today’s martyrs will be fuel for the resistance against them.”

In a statement, issued by Hamas, the movement claimed Fatah gunmen fired first, but people at the rally said they saw no evidence of this. Instead, they said it appeared the Hamas police simply opened fire.

Palestinian Arabs are more divided now than at any point in their history, with Fatah in control of only a few pockets of the West Bank ceded to them by agreements brokered with Israel in the 1990s. Gaza remains firmly in the hands of Hamas.

The chaos in Gaza adds to the difficulties faced by officials gathering for the Middle East peace summit, due to be hosted by President Bush in Annapolis, Md., at the end of the month.

The international community is banking on the Fatah leader, Mahmoud Abbas, signing up to a commitment to negotiate peace with Israel, but the situation in Gaza shows how he speaks for only part of the Palestinian Arab community. The deaths marred a long weekend of events to commemorate Arafat’s death on November 11, 2004.

On Saturday, a mausoleum and mosque were opened at the site of his grave in the West Bank town of Ramallah, although Palestinian Arabs from across the political spectrum said they hoped one day to see him re-interred in Jerusalem.