Palestinian President Mahmoud Abbas ordered security forces to deploy across Gaza yesterday after the killing of three young sons of one of his loyalists shocked Palestinians and stoked fears of internal strife.
Tension between the moderate Abbas and the governing Hamas Islamist group soared after the attack by unidentified gunmen on Monday.
The three children of a senior intelligence chief were shot dead as they arrived at school.
Early yesterday, heavily-armed members of those security forces that take their orders from Abbas took up positions around key installations and road junctions in Gaza City.
"Palestinian security forces deployed in all streets of Gaza City to prevent crime. This was upon orders from President Abbas," a Palestinian security source said.
A force loyal to the Hamas government also strengthened its positions in the coastal strip. There was no immediate sign of friction between the Abbas and Hamas loyalists, but fear of fresh clashes deepened sharply on Monday.
Scores of children on their way to school paid their respects at a mourning tent erected in Gaza City for the dead boys. They then set fire to tires in the streets to protest against the killings, sending thick clouds of black smoke into the air.
It was the first time children have been targeted in such an attack. Angry mourners firing guns stormed the parliament compound on Monday during the funeral for the boys, aged six to nine.
In the funeral, mourners held aloft the small bodies of the boys wrapped in white burial shrouds.
"I have no words. Words stop at the extent of this crime," said the bereaved father, Baha Balousheh. "I am a father who has lost his children."
A senior Palestinian intelligence official in the occupied West Bank said it was unclear who was behind the attack on Balousheh's children.
Both Abbas and Prime Minister Ismail Haniyeh, a senior Hamas leader, said they had urged the authorities to find the killers.
Fatah legislators demanded on Monday that Abbas dismiss the Hamas-led government. Amid universal condemnation of the shooting, the top Muslim cleric in Gaza called for the death penalty for the assailants.
Besides internal political unrest, Gaza is riven with clan fighting and a surge in crime following a Western aid embargo on the Hamas government that has deepened poverty.
Political tension has been rising over the failure of Hamas and the formerly dominant Fatah movement to form a unity government that Palestinians hope might end the Western boycott.
Abbas aides said on Saturday the president planned to call early elections after talks on a unity government foundered.
Hamas accused Abbas of trying to topple the government, which came to power after beating Fatah in elections last January.
Unity talks broke down over Hamas's rejection of Western demands that it recognise Israel, and its insistence on holding the interior and finance portfolios in any new government.
Abbas, a moderate who favours peace negotiations with Israel, was elected separately early last year.