Israeli forces responded with helicopter-launched missile attacks on separate targets in Gaza City, killing at least nine people.
Within an hour of the bus bombing, Israeli helicopters fired on the motorcade of Tito Massoud, a leader of the Palestinian militant group Hamas, an Israeli television report said.
It was the second attempt on a Hamas leader by Israeli forces in as many days. Israeli military sources said the strike was planned before the bombing in Jerusalem, CNN reported.
Pictures from site of the missile attack in Gaza showed firefighters dousing a group of badly damaged, smoking cars with water.
Israeli gunships fired on another target in Gaza just after midnight Thursday, local time, killing two people, according to the Associated Press.
Television news reports from the scene of the suicide bombing showed paramedics attending to victims near the scorched, twisted shell of the bus on a Jerusalem street.
“The explosion went off during afternoon rush hour on city bus No. 14 on Jaffa Street, Jerusalem’s main thoroughfare, near Mahane Yehuda, Jerusalem’s outdoor market which repeatedly has been targeted by Palestinian militants in the past,” AP correspondent Ravi Nessman reported from Jerusalem.
The AP reported that Hamas leader Mahmoud Zahar said the bus attack was “a message to all the Zionist criminals that they are not safe and that the Palestinian fighters are capable of reaching them everywhere.”
Israeli government spokesman David Baker told Reuters the bus attack “was another example of unbridled Palestinian terrorism which must be stopped immediately by the Palestinian Authority.”
The bus bombing came a day after the attempted assassination of Abdel-Aziz al-Rantissi, another Hamas leader, by Israeli forces. Rantissi was wounded when missiles fired from Israeli helicopters hit the car in which he was traveling. Hamas immediately vowed revenge.
The latest cycle of violence comes on the heels of a June 4 peace summit hosted by President Bush and attended by the Israeli and Palestinian prime ministers in Aqaba, Jordan.
On Wednesday, President Bush called on all nations to “fight off terror, to cut off money to organizations such as Hamas, to isolate those who hate so much that they’re willing to kill to stop peace from going forward,” the AP reported.
At the Aqaba summit, newly appointed Palestinian Prime Minister Mahmoud Abbas pledged to fight terrorism, while Israeli Prime Minister Ariel Sharon promised to begin dismantling unauthorized Israeli settlements in Palestinian areas.
Abbas had been attempting to negotiate a cease-fire with the Hamas but leaders of the group broke off the talks on June 6.
Abbas and Palestinian President Yasser Arafat both condemened the attacks. Arafat called on both sides to return to the negotiating table, the AP reported. Hamas reportedly reponded with a statement rejecting Arafat’s calls to stop the violence.
Sharon said Israel would “continue to pursue until the end the terrorists and those that send them.”