Updated

In a move that could wreck U.S. efforts to construct a truce, Israel cut off all contact with Yasser Arafat early Thursday following the death of 10 more Israelis at the hands of Palestinian militants in a bus ambush.

The Israeli Security Cabinet statement said the Palestinian leader was "directly responsible" for the attacks "and therefore is no longer relevant to Israel, and Israel will no longer have any connection with him."

Justice Minister Meir Sheetrit said Israel had reached "the moment of truth" in its battle against terrorism. "We have been talking with the Palestinians at all levels for two years," Sheetrit said. "Now it is time for Israel to defend itself."

The announcement was issued by the Cabinet just hours after Arafat bowed to long-standing Israeli demands and ordered the offices of the militant Hamas and Islamic Jihad groups closed.

Israeli helicopters targeted Arafat's Ramallah headquarters early Thursday shortly after he left the compound, Palestinian security officials said.

Israeli missiles hit the main transmitter of the Palestinian Authority's radio station, knocking it off the air, the military said.

U.S. envoy Anthony Zinni, in the region to negotiate an end to nearly 15 months of violence, instead issued another denunciation of Palestinian extremists. The White House had earlier said Wednesday's attacks would not derail Zinni's mission.

At a news conference with Sheetrit after the Cabinet meeting, Brig. Gen. Dan Harel, Israel's chief of military operations, said Arafat himself was not a target. The Cabinet, made up of senior ministers, said Israeli forces would be deployed around Palestinian towns to make arrests and confiscate weapons.

Sheetrit said there would be no more contact with Arafat or his Palestinian Authority and that meetings of security commanders, sponsored by Zinni, would cease.

Since Nov. 26, when Zinni arrived, 50 Palestinians and 44 Israelis have been killed in violence. The Palestinian toll includes 18 armed attackers and 10 suicide bombers.

Hamas said it was responsible for the bus attack just after nightfall Wednesday, which killed 10 and injured 30. The crowded vehicle was ambushed as it climbed a winding road near the Jewish settlement of Emmanuel in the West Bank, 25 miles north of Jerusalem.

Brig. Gen. Ron Kitrey said early Thursday that Israeli forces declared curfews and searched five villages near the scene of the bus attack, but made no arrests.

Wednesday's violence began after midnight with an Israeli helicopter strike that killed four Palestinian militiamen. This followed mortar fire on Jewish settlements in the southern Gaza Strip late Tuesday, which caused no damage or injuries.

In the bus ambush, two bombs planted on the roadside exploded, regional police commander Shahar Ayalon said. One or more gunmen then opened fire from surrounding hills.

Israelis troops fired back, killing one gunman and launching a search for others. Ayalon said the gunman had explosives strapped to his body. Palestinian security officials identified him as Mohammed Reihan, 25, a Hamas activist, whose brother was recently killed by Israeli troops.

The explosion blew out the windows of the bus, which started its journey near Tel Aviv. A body covered by a blanket lay by the side of the road. Windshields were shattered in nearby cars. One was driven into a ditch.

At almost the same moment but well to the south in the Gaza Strip, two suicide bombers blew themselves up near the Gush Katif settlement bloc, wounding several people, the army said. The assailants jumped on a car leaving the settlement and detonated the explosives, TV reports said. The passengers in the car escaped with minor injuries. The suicide bombers died.

There was no immediate claim of responsibility for the Gaza attack.

The Palestinian Authority condemned the attack but braced for an Israeli strike — which came within hours.

Arafat's organization also said in a statement: "The Palestinian leadership has decided to close all offices, centers and organizations and anything connected with Hamas and Islamic Jihad in the Palestinian territories."

This appeared to cover Hamas kindergartens and charities, but as of early Thursday, only a media office had been closed.

Hamas derives much of its public support from its charitable work, providing welfare to Palestinians hard hit by more than a year of conflict, while the Palestinian Authority itself is near bankruptcy.

Also Wednesday, Israeli F-16s bombed a Palestinian security compound in Gaza City at least three times, witnesses said. As four fighter planes buzzed overhead, there was a large explosion at the compound and white smoke filled the air. Two more blasts followed moments later. Ten people were hurt, none seriously, doctors said. A woman who was not wounded died of shock, they said.

Later, Palestinian security officials said, Israeli missiles struck the radar unit at Gaza Airport, where Israeli bulldozers destroyed the runway last week after previous Palestinian attacks.

In Nablus, another F-16 shelled a helicopter pad in a compound belonging to Force 17, an elite Palestinian security unit. An Israeli army spokesman said attacks had also targeted a naval police headquarters in Sudaniyeh, in the northern Gaza Strip.

No injuries were immediately reported in the strikes.

Electricity in Gaza City had been cut off earlier to darken the area in anticipation of the retaliation. Electricity was also cut in the West Bank city of Ramallah. Arafat and a few bodyguards stayed bunkered at his headquarters there.

Palestinian militants have ignored Arafat's calls for a cease-fire. Israel reserved the right to strike back at the Palestinian Authority for attacks by the militants and dismissed as a sham Arafat's recent arrest of 180 militants.

"The Palestinian leadership reiterates that it is working intensively and continuously to restore quiet and security despite the Israeli escalation, the raids and the assassinations [of militants] and the closure imposed on all the Palestinian cities and villages," it said in a statement.

The latest cycle of violence began nearly 15 months ago. Since then, 818 people have been killed on the Palestinian side and 242 on the Israeli side.

The Associated Press contributed to this report.