Palestinian gunmen stormed into a Gaza City (search) hospital twice on Monday and killed men convicted of collaborating with Israeli intelligence, hours after they were admitted for wounds suffered when a grenade exploded in their jail cell.

The dead, identified as Mahmoud al-Sharef, 52, and Walid Hamdiyeh, 42, were slain in similar attacks at Shifa Hospital (search) a few hours apart.

Hamdiyeh confessed during a 2002 trial to providing Israel with information that helped its forces kill Imad Akel, a founder of the Hamas (search) military wing, in 1993. Al-Sharef was convicted in 1999 of being involved in the killing of Mahmoud al-Khawja, the founder of Islamic Jihad's (search) military wing, four years earlier.

The killings of collaborators are relatively common in the Palestinian territories, but these came amid growing lawlessness that has highlighted the inability of police to rein in violence.

In the West Bank town of Ramallah (search), hundreds of Palestinians rallied Monday in support of Palestinian leader Yasser Arafat (search), who has been criticized recently because of lawlessness and corruption.

"You are the defenders of the sacred land," Arafat told the crowd, praising supporters for thwarting what he said was a conspiracy against him.

In the northern Gaza Strip overnight, Israeli troops shot and killed three armed Palestinians next to a Jewish settlement.

The Israeli military said a group of men was spotted approaching the settlement's perimeter fence and soldiers opened fire. A joint announcement from the Palestinian militant groups Islamic Jihad and Al Aqsa Martyrs' Brigades said three of their men were killed in what they called a "heroic operation."

There were no Israeli casualties.

The funeral procession for one of the militants, including mourners carrying assault rifles, was outside Shifa Hospital when five masked gunmen entered the building and went to al-Sharef's room.

One gunman shot al-Sharef twice in the head with a pistol as he lay in his hospital bed, police said.

He was one of seven prisoners wounded earlier Monday in Gaza Central Prison by two crude hand grenades, Palestinian security officials said.

One of the wounded, Musa Ouda, 30, died of his wounds, they said.

The explosions were in a wing reserved for men convicted of collaborating with Israel.

In the second attack at the hospital, about 20 gunmen raced up to the hospital in four vehicles, closing the street. Four gunmen ran to the intensive care unit, where they shot Hamdiyeh three times, killing him.

Also Monday, Israeli forces entered the Khan Younis refugee camp, in southern Gaza, and demolished six buildings. Troops opened fire, and a woman was killed when a bullet came through her window, residents said. Doctors said six civilians were wounded.

Israeli military officials said the operation was aimed at the "terrorist infrastructure" in the camp. The officials said Palestinians used the location to fire mortars and rifles at a nearby Jewish settlement. They said helicopters fired warning shots at an open area to keep gunmen away.