Police say at least three Israelis are dead and six wounded after a suicide bomber blew himself up in a bus near the city of Hadera.
Police say an explosion blew apart the bus that was traveling from Nazareth to Tel Aviv.
Police say a suicide bomber caused the explosion and that parts of his body were found at the scene.
The bus was near a military base when the bomb went off, blowing the sides off the vehicle, which stood next to the highway in a tangle of twisted metal.
U.S. envoy and retired Marine Corps General Anthony Zinni, who is here trying to negotiate a cease-fire, issued a statement saying "these vicious terror attacks must stop now if we are to create the environment that leads to peace."
Israeli government spokesman Avi Pazner said Palestinian leader Yasser Arafat is responsible for the bombing, which he says is designed to block attempts to reach a truce. "We have seen an increase in recent days of the terrorist activity of the Palestinians and this is in order to undermine the peace mission of General Zinni because the Palestinian Authority is not interested at the present time to reach a cease-fire. They want to continue violence. They want to achieve an escalation in violence," he said.
A Palestinian Authority spokesman condemned the attack, saying officials have been told to track down and arrest those behind it.
In other violence, one Israeli soldier was killed and another wounded in a drive-by shooting near a Palestinian village close to the boundary that separates Israel and the West Bank.
In another incident, Israeli soldiers shot and killed two Palestinians at a checkpoint in the Jordan Valley.
Earlier, Israeli Prime Minister Ariel Sharon reiterated Israel will not negotiate with the Palestinians without one week of complete quiet. "It will be seven days, not one hour less. I made it very clear from the first day that the government I lead will not negotiate under pressure of terror and violence," he said.
Prime Minister Sharon is heading for the United States and is scheduled to meet President Bush and other top officials early next week.