Hejazi's family claimed he was taken to the roof and executed by the Israeli police. His sister, Shayma'a, said he was dragged to the rooftop by a large squad of heavily armed police, beaten and shot.
Police said they had tried to arrest Hijazi but that, after he opened fire at them, they pursued him on to the roof, where he was shot and killed.
Police said Hejazi was the main suspect in the attempted assassination of Yehuda Glick, 48, a Right-wing rabbi and leading campaigner for prayer rights for Jews on Jerusalem's flash-point Temple Mount - which is revered by Muslims as the al-Haram al-Sharif.
Witnesses said he approached Glick after a conference at the Menachem Begin Heritage Centre on Thursday and - after establishing his identity - shot him in the chest and abdomen before escaping on a motorcycle.
Glick was said to be in a stable condition yesterday.
It emerged that Hejazi worked in the restaurant of the Begin Centre - which hosts regular conferences by Israeli Right-wing organisations - raising questions of a serious security breach, given his past record as a prison inmate.
Israeli security chiefs responded to the shooting by closing the Haram al-Sharif compound, which is the third holiest site in Islam but also revered as the most sacred site in Judaism by many religious Jews because it is the presumed location of two ancient temples.
The site was reopened on Thursday night after being closed for most of the day.
It was the first time it had been ordered totally closed since a violent outbreak following a visit by the late Ariel Sharon, Israel's former Prime Minister, in 2000, an event that ushered in the second Palestinian intifada.
Abbas' response seemed to suggest that the latest decision could have similar consequences.
"This dangerous Israeli escalation is a declaration of war on the Palestinian people and its sacred places and on the Arab and Islamic nation," said Nabil Abu Redeineh, Abbas' spokesman.
"Harming the places sacred to Muslims and Christians is a red line. The state of Palestine will take all legal measures to hold Israel accountable and to stop these ongoing attacks."
Benjamin Netanyahu, Israel's Prime Minister, said Abbas bore responsibility for the shooting of Glick, accusing the Palestinian leader of incitement and the international community of hypocrisy for not condemning him.
Nevertheless, the Israeli leader signalled a willingness to reduce tensions by pledging to maintain the "status quo" in Jerusalem's holy sites - meaning that he would oppose the attempts of Jewish radicals to win the right to pray on the Temple Mount/Haram al-Sharif.
"We must first of all lower the flames. No side should take the law into its own hands," Netanyahu said. "We must be level-headed and act with determination and responsibility, and so we shall."
There was little sign of temperatures being lowered in Abu Tor, an area straddling East and West Jerusalem. The sounds of unrest - including angry pronouncements from mosques - could still be heard more than 12 hours after Hejazi's death.
