GAZA CITY, Gaza Strip (AP) _ Israeli forces with dozens of tanks and attack helicopters pushed into the Rafah refugee camp on Saturday, killing three men in one of the largest military incursions into the Gaza Strip in 30 months of fighting, Palestinians said.

Israeli military officials, speaking on condition of anonymity, said the army was operating in the Rafah area, but would not give details.

At least 35 Palestinians _ including three women _ were shot and wounded by the Israeli troops, witnesses said. Two men in their 20s and a 15-year-old were killed, Palestinian doctors said. Another four people were in critical condition.

The Israeli forces penetrated the refugee camp from three directions using more than 35 tanks and armored personnel carriers, bulldozers and jeeps. Five attack helicopters circled above, flashing spotlights above the densely populated area, where about 60,000 live.

The incursion appeared to have targeted the Yibna neighborhood, one of two known militant strongholds in the Rafah refugee camp.

Tanks reached the Rafah camp's center and surrounded the main market. The crackle of gunfire could be heard all around, residents said.

``I was sitting outside with some friends playing cards when suddenly we came under fire,'' said Marwan Khatib, 39, who lives in the camp, which is less than 3.5 kilometers from the Egypt border. ``Bullets hit the wall next to us and tanks were coming toward us very fast.''

Soldiers knocked out electricity in part of the Rafah camp, casting darkness over sections, witnesses said. Phone lines were also reportedly down.

Ambulances could be heard rushing to the area with sirens wailing. Palestinian television broadcasts were urging residents to stay indoors.

Dr. Ali Mussa, director of Najar Hospital in Rafah, said army gunfire was preventing medical personnel from reaching more wounded. It was unclear how many others were injured.

Rafah Mayor Said Zourab said undercover soldiers were raiding homes, and troops were in control of most of the camp. ``It's a real war,'' Zourab said.

The Rafah camp has been a flashpoint of tensions between Israeli troops and Palestinians.

A British peace activist who witnesses said was shot by Israeli troops in Rafah on April 11 remained in serious condition Saturday, registering scant brain activity.

``The outlook isn't promising,'' said Anthony Hurndall, 52, of London, referring to his son Tom. ``They've managed to keep him going, but he's at the bottom of the scale for brain activity.''

Tom Hurndall, 21, was shot in the head by Israeli fire, witnesses said. The shooting was witnessed by a a photographer on assignment for The Associated Press.

A dozen activists had walked toward Israeli tanks on the outskirts of Rafah. They wanted to set up a tent to block Israeli military incursions and were joined by several children, said photographer Khalil Hamra. When Hurndall tried to get two children out of the line of fire a tank shot him in the head, Hamra said.

Hurndall was a volunteer with the International Solidarity Movement, a group based in the West Bank and Gaza. Two months before, he had been in Baghdad working as a human shield.

The army has said it is investigating the shooting.

Another peace activist with the group _ Rachel Corrie of Olympia, Washington _ died March 16 in Rafah trying to stop an Israeli bulldozer during a military incursion.