Tensions were running high in Gaza yesterday after Hamas police killed seven people at the biggest demonstration by the rival Fatah party since it was ousted by the Islamists in June.
Palestinian President Mahmoud Abbas has declared a three-day period of mourning to "pay homage to the martyrs killed by the bullets of the putschists," referring to Hamas.
Flags will be flown at half-mast on official buildings in the West Bank, while families in Gaza mourn those killed on Monday when Hamas-run police opened fire on a rally of hundreds of thousands of people commemorating the death of Yasser Arafat.
Another 130 people were wounded when Hamas gunmen opened fire as crowds threw rocks and chanted "Shiite, Shiite" -- accusing the Islamists of being a proxy for Shiite Iran and its ally Syria, witnesses and medics said.
The Palestinian Authority's official newspaper Al-Hayat al-Jadid called the shootings a "massacre."
"The most recent massacre by the [Hamas-run] Executive Force militia is the product of a cruel mentality that from the very beginning has wanted the situation in Gaza to reach a point of no return," it said.
The leading Al-Quds newspaper said the rally had unexpectedly become a "referendum" on the Hamas movement's five-month-long rule in the impoverished and increasingly isolated coastal strip.
"Everyone who went out into the streets yesterday did so, not for the commemoration of Abu Ammar [Yasser Arafat] but to voice their opposition to the current situation in the Gaza Strip," it said.
The deaths have deepened already bitter divisions among Palestinians, with Palestinian Prime Minister Salam Fayyad on Monday blaming top Hamas leaders for the killings.
"Senior officials in Hamas ordered these crimes which were carried out by the Hamas militia in order to terrify the people ... Now their punishment is a national duty," Fayyad said in a statement.
On official television, Abbas denounced "these horrible crimes committed by a band of rebels ... before the eyes of the entire world."
Hamas blamed Fatah gunmen for instigating the clashes, accusing them of firing down on police from the rooftops around the square.
They "opened fire on Palestinian police, wounding four of them, then a group within the rally started throwing rocks at police, and the clashes ensued," Hamas spokesman Sami Abu Zuhri said at a press conference on Monday.
His account was disputed by an Agence France Presse correspondent and several witnesses, who said Hamas police opened fire on the demonstration.
The rally saw the city center filled with a sea of the yellow flags of the Fatah party founded by Arafat and currently led by Abbas, whose forces were driven from the Gaza Strip in a bloody Hamas takeover in mid-June.
The crowds waved Palestinian flags and held portraits of the iconic leader in his trademark black-and-white headdress as Fatah party officials called for unity over loudspeakers.
Hamas, which has controlled the Gaza Strip since the takeover five months ago, broke up several smaller Fatah demonstrations on Sunday -- the third anniversary of Arafat's death -- shooting and wounding three people.
Palestinians across the occupied territories, more divided now than at any other point in their history, have been paying tribute to Arafat who died on Nov. 11, 2004, and who remains a symbol of Palestinian unity.