Israel razed the homes of two Palestinian homicide bombers Thursday, and a 12-year-old Palestinian boy breaking curfew to buy cigarettes for his father was killed by Israeli army fire, a witness said.

The army said it was looking into the killing of the boy.

The demolition of the bombers' homes came before a homicide bomber killed five Israelis on a bus in Tel Aviv, and a day after an Islamic militant blew himself up at a bus stop in northern Israel, killing himself and a policeman, and wounding another officer and a bystander.

The explosion ended a six-week lull in attacks on Israeli civilians. An Israeli motorist and a Jewish settler died in Palestinian shooting attacks Wednesday.

Israel had attributed the relative calm to its strong military presence in the West Bank; Israeli troops control six of eight main population centers, and have been confining hundreds of thousands of Palestinians to their homes since mid-June.

Israeli police commissioner Shlomo Aharonishki said Thursday that Palestinian militants have been trying hard to break out of the army's chokehold. "We need to be grateful for every day that passes without an attack," he told Israel Army Radio.

The militant Islamic Jihad group claimed responsibility for Wednesday's suicide attack. In a statement on the Lebanese TV station Al Manar, the group did not identify the bomber, apparently to try to shield his family from Israeli reprisals.

Israel has been using increasingly tough measures against militants' families. Israel has demolished some three dozen homes of terror suspects, and has expelled a brother and sister of an alleged bombing mastermind to the Gaza Strip.

In Abu Dis, a West Bank suburb of Jerusalem, bulldozers on Thursday razed the homes of Osama Nidbahar and Nabil Khaldaiya who blew themselves up on Jerusalem's Ben Yehuda pedestrian mall on Dec. 1, killing 11 people and wounding 80.

The families of the bombers had appealed to Israel's Supreme Court to prevent the demolitions, insisting that they never knew of the militants' intentions. The court rejected the petitions earlier this week.

Israel has also been enforcing prolonged curfews in most Palestinian towns in the West Bank to prevent militants from reaching Israel.

In Ramallah, Abdel Salam Samreen, 12, was killed by several shots to the chest as he was walking on the street near his home.

The boy's mother, Wafiqa, said her husband had sent him to a nearby grocery to buy cigarettes. She said five minutes after her son left the house, someone came to tell her he had been shot. "He was there, lying on the street with six shots in the chest," she said, crying.

Amar Samir, a witness, said the boy was crossing a street when he saw an Israeli tank nearby. "He ran away and tried to hid behind a wall, and they (soldiers) started shooting at him," Samir said.

In other developments, the head of Israel's Shin Bet security service, Avi Dichter, told the Cabinet on Wednesday that it appears Jewish militants may have been responsible for 12 terror attacks against Palestinians.

Dichter did not suggest there was an organized Jewish underground and did not say if one person or group was responsible for more than one attack, Israeli officials said.

Prime Minister Ariel Sharon told the Cabinet that he has instructed the Shin Bet to step up efforts to catch those behind the attacks, which he said were not only "morally grave" but also posed potential "diplomatic complications" for Israel.