A local religious leader who was a frequent critic of the Islamic militant group Hamas was killed in a drive-by shooting Friday as he walked out of a Gaza mosque, witnesses and medical officials said as violence seemed to be spiraling out control in the area.

There was no claim of responsibility in the death of Adel Nasar, who was shot by gunmen who were waiting in a car outside the mosque in the Mughazi refugee camp in central Gaza. Nasar was not openly affiliated with any political party, but he was a well-known in the refugee camp and often spoke against Hamas in his sermons.

More than two dozen people have been killed in a month of fighting in Gaza between Hamas and the rival Fatah movement.

Tensions between the sides have been high since Hamas defeated Fatah in parliamentary elections one year ago. Amid the tensions, Gaza has been plagued by crime and lawlessness, including dozens of kidnappings and shootings to settle personal scores.

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The shooting came after Hamas gunmen killed a senior Palestinian security commander and four of his guards at his Gaza home, and Israeli forces killed four people in the West Bank during an arrest raid, drawing harsh criticism from Egypt's president.

Palestinian President Mahmoud Abbas of Fatah and Prime Minister Ismail Haniyeh of Hamas met early Friday in Gaza and agreed to work to defuse the tensions and pull back their forces, Haniyeh told reporters. "We are going to end all armed displays in the streets," he said. Abbas had no comment.

The body of Col. Mohammed Ghayeb, chief of the Preventive Security Service in northern Gaza, riddled with bullets and mutilated by stab wounds, was found in his home in northern Gaza Thursday after a daylong battle with Hamas gunmen. The killing of the senior officer was likely to spark reprisal raids.

In several places in the West Bank late Thursday, Fatah militants attacked Hamas offices and vehicles. One Hamas activist was wounded, Palestinian security officials said.

Ghayeb was on the phone to Palestine TV just moments before his death and appealed for help as his house came under attack. "They are killers," he said of the Hamas gunmen. "They are targeting the house, children are dying, they are bleeding. For God's sake, send an ambulance, we want an ambulance, somebody move."

The battle outside the house raged for much of the day and killed four of Ghayeb's guards and a Hamas gunman. About three dozen people, including eight children, were also wounded.

During the standoff outside Ghayeb's home in Beit Lahiya, dozens of women rushed into the streets in protest, chanting "Spare the bullets, shame, shame."

The persistent factional fighting — large-scale confrontations began in Gaza a month ago — are a result of the political deadlock between Hamas, which controls the Cabinet, and Abbas, who was elected separately and also wields considerable power.

The Israeli raid in the West Bank, which turned downtown Ramallah into a battlefield with dozens of cars smashed and vegetable carts overturned, further undercut Abbas in his increasingly violent power struggle with Hamas.

The raid started out as a routine arrest operation but quickly escalated into a major clash. Militants discovered the undercover soldiers as they burst into a vegetable market and opened fire on them, forcing Israel to send in reinforcements. Four Palestinians were killed and 20 wounded in the fighting. The Israelis eventually left after detaining four suspects.

For about two hours, a heavy battle raged in the normally quiet city, sending residents scrambling for cover. Bursts of gunfire, loud booms and ambulance sirens could be heard across Ramallah. At one point, a helicopter fired large-caliber bullets in what the army said was deterrent fire.

It was the first major raid since the Israeli and Palestinian leaders agreed to try to ease tensions between the sides.

Israeli Prime Minister Ehud Olmert, who met with Egyptian President Hosni Mubarak just a few hours after the Ramallah raid, apologized for any civilian casualties, but said the raid was intended to protect Israel from terrorist attacks.

"Things developed in a way that could not have been predicted in advance. If innocent people were hurt, this was not our intention," he said.

The summit had been intended to push for new Israeli-Palestinian peace efforts, but was overshadowed by the violence.

Standing next to Olmert in the Red Sea resort of Sharm El-Sheik, Mubarak condemned the raid. "Israel's security cannot be achieved through military force but by serious endeavors toward peace," he said.

Abbas said in a harshly worded statement that Israel's peace promises rang hollow in light of the raid and demanded $5 million in compensation for the damage to shops and cars in Ramallah.

Israeli Cabinet minister Binyamin Ben-Eliezer, a former defense minister, criticized the raid's timing. "I don't think this operation should have been carried out on the day of a visit by the Israeli Prime Minister to a country in which we have a supreme strategic interest," Ben-Eliezer told Israel Radio on Friday morning. "Our relations with Egypt are more important to us than anything else."

The apparent target of the raid, Rabih Hamed, escaped with serious injuries. A photographer for the local news agency Maan was critically wounded by a gunshot to the head.