Jerusalem ? The Israeli and Palestinian prime ministers failed Saturday to narrow sharp differences over a U.S.-backed peace plan in a three-hour summit — the first since fighting erupted nearly three years ago — that was overshadowed by violence before and after the summit.

A suicide bomber blew himself up on a Jerusalem bus early today, killing himself and at least seven passengers. At least 20 others were wounded, four in serious condition. On the outskirts of the city, another bomber blew himself up.

Today’s bombings were part of a sudden surge in Palestinian attacks — four in 12 hours — including a bombing in the West Bank city of Hebron in which an Israeli husband and wife were killed. Also, two armed Palestinians tried to attack a Jewish settlement in the West Bank and were killed by soldiers.

The attacks appeared to be timed to coincide with a summit between the leaders of Israel and the Palestinians.

At the start of the meeting, Israeli Prime Minister Ariel Sharon expressed his “rage” about the Hebron attack, a Sharon statement said. Palestinian Prime Minister Mahmoud Abbas “agreed that stopping terrorism is the first step toward any progress,” the statement said.

Early today, Sharon canceled his trip to Washington in wake of the suicide bombings. He was to talk with President Bush about the Mideast peace plan.

Palestinian Parliament Speaker Ahmed Qureia, who attended the meeting, said the Palestinian delegation asked Sharon to accept the “road map,” a three-stage prescription for ending violence quickly and setting up a Palestinian state by 2005.

Sharon declined, and said he first had wanted to discuss his reservations with Bush.

Qureia said Sharon also proposed withdrawing troops from some areas of the West Bank and Gaza Strip. Israeli media have reported that Sharon would offer to pull out soldiers from parts of the northern Gaza Strip as a test for Palestinian security forces who then would be expected to prevent rocket fire on Israel.

The summit could be a bellwether for future U.S. mediation efforts. If top-level Israeli-Palestinian talks can’t produce results, Washington might have to press the sides harder or even consider imposing solutions. Bush has not spelled out how far he is willing to go in ensuring progress on the “road map.”

Abbas asked Sharon to lift travel bans on Palestinians, particularly on leader Yasser Arafat, and to stop hunting suspected militants so that the Palestinians could launch their own campaign against militias, Qureia said.

Israel said it would not budge until Abbas had taken real steps against the armed groups, including arrests and weapons sweeps.

Responding to the Sunday morning attack, David Baker, an official in Sharon’s office, said the Palestinian Authority must use “all means available” to stop the attacks. “Palestinian terror cannot rule the Palestinian agenda,” he said.

The bus bomber struck at a few minutes before 6 a.m. today, a work day in Israel, at the beginning of rush hour.

Witnesses said the bomb went off on a large bus divided into two sections as it neared a bridge in one of Jerusalem’s largest intersections, outside the Arab neighborhood of Shuafat and the Jewish neighborhood of French Hill, in the part of Jerusalem that Israel captured in the 1967 war — an area that is also claimed by the Palestinians.

Police said the second bomber blew himself up at the entrance to the village of Dahiya el-Barid, near Jerusalem. Police said the bomber was killed in the blast on the highway, and no one else was hurt.

In violence Saturday, a Palestinian disguised as an observant Jew blew himself up in a downtown square in Hebron, near Jewish settler enclaves. The bomber killed an Israeli man and his pregnant wife.

The assailant was later identified by relatives as Fuad Qawasmeh, 21, a supporter of the Islamic militant group Hamas, which has carried out scores of attacks on Israelis since the outbreak of fighting in September 2000.

Palestinian militias have threatened to sabotage the road map for peace, saying they would not halt attacks and would resist forcefully if Abbas tried to disarm them.

As the meeting between Abbas and Sharon was ending, two Palestinian gunmen tried to enter the Jewish settlement of Shaarei Tikvah in the West Bank but were killed by security forces near the perimeter fence.

In the Gaza town of Beit Hanoun, Israeli troops killed a Palestinian gunman in clashes.