A Palestinian militant group pledged Sunday to unleash an "earthquake" of vengeance on Israel for killing seven fugitives, including the most wanted militant in the West Bank, during a raid in Nablus.

Israeli troops found the militants after a gunman they were chasing through a house Saturday slipped into a secret underground tunnel where they were all hiding. The killing of the fugitives, from Hamas (search), Islamic Jihad (searchand the Al Aqsa Martyrs' Brigades (search), was the main goal of a three-day operation in Nablus, the army said.

Shortly after the fugitives -- including the Nablus Al Aqsa commander, Nayef Abu Sharkh (search) -- were killed, troops began withdrawing from the center of the city where they had been conducting house-to-house searches for the militants. The army said Sunday it had ended its broad operation in the city, which it has labeled a "hornet's nest" of terrorist activity, but continued with routine patrols.

About 20,000 people, including terrorists from all three groups, marched through the city Sunday in a funeral procession for the men, many chanting "revenge, revenge."

Dozens of armed men fired in the air, and some called Palestinian Prime Minister Ahmed Qureia (search) a "cockroach," in apparent frustration with his inability to stop the raids.

Speaking in Ramallah, Qureia called the raid a "criminal, barbaric act."

"This crime shows that Israel is continuing its strategy of killings and assassinations against all the Palestinians," he said.

Israeli Prime Minister Ariel Sharon (searchpraised the raid as an "impressive success" in Israel's war on terror, but Abu Mahmoud, an Al Aqsa spokesman, said his group would retaliate.

"The revenge will come like an earthquake for the state of Israel, maybe hitting the citizens, maybe the soldiers, maybe the government. But at the right time and the right place they will be hit," he said.

Israel has struck hard at militant groups since fighting erupted more than three years ago. In the past few months, the army struck down a top Hamas leader and his successor in air strikes.

Israel has repeatedly targeted Al Aqsa, a terrorist group affiliated with Yasser Arafat's (search) Fatah movement that has carried out dozens of attacks, including suicide bombings, against Israelis. The group is made up of disparate cells with no unified leadership.

With Sharon's plan to withdraw from the Gaza Strip looming, the Palestinian Authority is trying to reach a truce deal with Al Aqsa and other Palestinian factions.

Egypt has pledged to assist training and reforming Palestinian security forces so a Gaza handover will go smoothly, but has made its help conditional on a cease-fire between the factions.