Palestinians expressed anger Saturday at an overnight homicide bombing in Tel Aviv (search) that killed four Israelis and threatened a fragile truce, a departure from former times when they welcomed attacks on their Israeli foes.

Official condemnations and denials were followed by public anger toward the perpetrators as Israel (search) blamed Syria and the Palestinian militant group Islamic Jihad (search), which claimed responsibility for the attack. The Palestinians pointed fingers at the Lebanese guerrilla group Hezbollah. Syria denied the allegations.

Palestinian leader Mahmoud Abbas (search) convened his top security chiefs directly after the bombing and issued a strong statement pledging to track down and punish the culprits. The three main Palestinian militant groups — including Islamic Jihad — initially denied involvement. A branch of the Al Aqsa Martyrs' Brigades in the West Bank city of Nablus even condemned the attack.

"We will not allow anyone to sabotage our national goals, aspirations and ambitions," Abbas said Saturday in the West Bank town of Ramallah. "All Palestinian factions, including the prisoners, were outraged by this operation. I emphasize that there is another party that wants to sabotage the peace process."

Palestinians, weary after four years of violence, welcomed an Israeli-Palestinian cease-fire declaration at a Mideast summit in Egypt on Feb. 8, and many accused Hezbollah of intentionally trying to destroy the truce.

"If Hezbollah was behind this attack, I as a Palestinian tell them, 'Deal with your own problems and stay out of ours,"' said Akram Abu Sbaa, 38, of Jenin.

Another Jenin resident, Bashar Jalloudi, 40, said Hezbollah's alleged involvement in the Tel Aviv bombing would only hurt Palestinian interests at a time of relative calm.

"Where was Hezbollah when we were being killed and our homes were being demolished? They were standing on the sidelines watching with their hands tied," Jalloudi said.

Friday night's bombing, carried out by an attacker from the West Bank town of Tulkarem, killed four people and wounded about 50 others.

If a Palestinian group is found responsible, it could derail the cease-fire and put tremendous pressure on Abbas to crack down, as Israel has demanded. If an outside group was involved, Israel is likely to give him more leeway.

Israel blamed Syria and Islamic Jihad. Palestinian security officials said Hezbollah was to blame. Both Islamic Jihad and Hezbollah receive backing from Damascus.