A Palestinian suicide bomber killed himself at a northern Israel bus stop Sunday, hours after five Palestinians were gunned down by Israeli troops.

Eleven were injured in the bomb blast in the port town of Haifa, none seriously, authorities said.

Elsewhere, 30 suspected militants were detained in Israeli raids on two West Bank villages.

With explosives strapped to his body, 20-year-old Nimr Abu Sayfien of Yamoun in the northern West Bank blew himself up at a bus stop in a busy intersection Sunday. Flames leapt from his body as a firefighter ducked behind a traffic barrier.

Sayfien was the only person to die in the latest attack which, according to the note he left behind, was an act of revenge for Israel's killing 10 days ago of Mahmoud Abu Hanoud, a top militant of the Hamas group.

No group immediately claimed responsibility for Sunday's incident, though Hamas has said it orchestrated the attacks in Haifa and Jerusalem a week ago that left 26 dead and set off the latest round of violence.

An Israeli official, speaking on condition of anonymity, said the bomber planned to set off two explosions: first a small blast, drawing rescue workers to the scene, and then a larger bomb strapped to his body; the bomber detonated the first explosive early as he was spotted by police, and the second bomb was defused.

Palestinian leader Yasser Arafat, interviewed by The Associated Press at his Ramallah headquarters hours before the latest bombing attack, called on the United States to press Israel to stop its assaults on the Palestinians and pledged to crack down on the militants staging a campaign of terror in Israel.

Israel, however, seemed unimpressed with his promises and efforts. Convening a Cabinet meeting at the nearby Israeli military headquarters in the West Bank, Israeli Prime Minister Ariel Sharon said: "In light of what is going on, we will apparently have to increase our [military] activity."

Sharon did not give details, but there has been speculation that Israeli troops might take over a West Bank town such as Jenin, from which many of the recent attackers have come.

Secretary of State Colin Powell, speaking during a flight from Kazakstan to Moscow, condemned the bombing and called on both sides "to do everything necessary to get violence down to zero."

Powell said both sides have taken actions that have "not moved us toward a peace process," but he added, "I think the burden right now is on Mr. Arafat to do more to get the violence down to zero."

In the West Bank a few hours before Sunday's explosion, Israeli forces entered the Palestinian town of Anabta — east of the town of Tulkarem in an area formally under Palestinian security control — killing four Palestinian policemen in an exchange of fire, said Tulkarem Governor Izzadine al-Shariff.

An army statement said troops were conducting searches and arresting "people engaged in terrorist activity."

Anabta Mayor Hamdallah Hamdallah told the Palestinian news agency Wafa that the four were shot "in cold blood." The army said the Palestinians had opened fire on the soldiers and the soldiers returned fire.

Palestinians said Israeli forces briefly took over two floors of the village council building used by the police and Force 17, an elite unit of Arafat's security that was declared a terrorist group last week by Israel's Cabinet. Hamdallah said Israeli forces arrested 25 people in his village.

In another incursion, Israeli soldiers detained five Palestinians in the village of Ramin, the military said. One was wounded in the village, which is under joint Israeli-Palestinian control.

Also Sunday, a Palestinian taxi driver was shot and killed by Israeli soldiers near Jenin, Palestinians said. They said he was trying to enter Jenin, which Israel's army has sealed off. The Israeli military had no comment.

In 14 months of violence, 807 people have been killed on the Palestinian side — a figure that includes 31 suicide bombers — and 232 people have been killed on the Israeli side.

The two attacks a week ago led Israeli Prime Minister Ariel Sharon to cut short his visit to the United States. Israeli air force planes and helicopters hit Palestinian police and security facilities in the West Bank and Gaza, and Israel's Cabinet declared the Palestinian Authority an "entity that supports terrorism."

The pressure on Arafat has also been strong from the United States. Senate Majority Leader Tom Daschle last week said the recent attacks "ended any patience the world had for excuses and inaction by Arafat" and echoed demands by Bush administration officials for a more serious crackdown.

In Saturday's interview with the AP, Arafat said he had arrested 17 key militants from a list of 33 relayed by U.S. officials and that he would continue the effort. But he called on the United States to do more to end Israel's attacks on Palestinian Authority installations.

"I am looking for them [the Americans] to make more pressure," he said.

The Associated Press contributed to this report.