Seven masked commandos burst into the home of PLO military chief Khalil al-Wazir early Saturday and opened fire with submachine guns, killing him, two bodyguards and a gardener.

Government and PLO officials said al-Wa-zir fired back with a revolver, but his body was riddled by about 170 bullets. PLO sources in Cyprus and Tunisia said a second group of commandos provided cover outside the building, but those reports were not confirmed.Leaders of the Palestine Liberation Organization blamed Israel for the killings in suburban Tunis. Palestinians protesting the slaying rioted in the Israeli-occupied territories and Israeli soldiers killed more than a dozen Arabs in the worst single-day toll since violence against the occupation began Dec. 8.

Al-Wazir, 52, also was called Abu Jihad (Father of Holy War). He was the most senior Palestinian official assassinated since the Fatah, the largest guerrilla group in the PLO, was founded 1964.

He was PLO chairman Yasser Arafat's closest aide, a member of the Executive Committee and the No. 2 man after Arafat in Fatah. He led Fatah's troops, the main PLO force, and supervised military operations inside the Israeli-occupied Gaza Strip and West Bank.

The PLO said the assassination team, which included a woman, fired about 170 bullets into al-Wazir's body. The commandos escaped, and Tunisian sources said three vehicles possibly used in the early morning attack were found on a beach about 25 miles north of Tunis.

Israel gave no official reaction to the kill-ings, and U.S. officials refused to comment on whether the Israelis were responsible.

Arafat, who was in Bahrain at the time, was "quite shocked and angered," said a PLO source there, speaking on condition of anonymity. Arafat went later to Saudi Arabia and then on to Tunis.

A special investigation commission formed by President Zine el-Abidine ben Ali of Tunisia said in a preliminary report Saturday night a commando group "armed with silenced submachine guns and pistols, made up of seven members, including a woman, attacked the residence of Abu Jihad at 1:30 a.m."

It said the killers fired "several bursts at the Palestinian leader, his two bodyguards . . . and a Tunisian gardener" and al-Wazir responded "using his personal revolver before being hit in different parts of his body."

"The commandos immediately left on the road to the forest of Raoued, about 40 kilometers (25 miles) north of Tunis aboard three vehicles, a Peugeot 305 and two Volkswagen minibuses, found abandoned by their occupants Saturday at dawn," the report said.

It said the investigation indicated the vehicles had "been rented under false identities."

Palestinian officials vowed to intensify the guerrilla war against Israel and the uprising of Palestinians in the West Bank and Gaza.

The PLO is an umbrella group for eight Palestinian factions, including Fatah. Three PLO groups and a guerrilla organization outside it challenge Arafat's loyalists.

PLO officials said al-Wazir was in the study of his house reading when the attackers drove up, killed a Tunisian bodyguard in a car outside, then burst into the house and killed a Palestinian bodyguard and a gardener.

"They then broke into Abu Jihad's study," said a PLO spokesman who refused to give his name. "Everything happened within seconds. He had drawn his pistol to defend himself, but they mowed him down."

Al-Wazir's wife, Intisar, his daughter Hanan, 14, and son Nidal, 2, the youngest of his five children, were in the house at the time but were unhurt.

Palestinian officials said al-Wazir's wife told Tunisian authorities that the attackers were masked, dressed in military fatigues and armed with silenced weapons.