Israeli troops clashed with Hamas (search) militants in Gaza on Saturday, killing two of them and a bystander in a shootout in a refugee camp where Israel has been conducting raids for more than a week.

Another Palestinian was killed in the West Bank town of Tulkarem (search) when Israeli soldiers fired on crowds of Palestinian youths who had thrown stones and a firebomb.

Meanwhile, a team of FBI explosives and forensics specialists continued its investigation Saturday into the bombing attack on a convoy of U.S. officials in Gaza that killed three Americans on Wednesday, U.S. Embassy spokesman Paul Patin said.

The team met Friday for several hours with Palestinian police commanders at an Israeli checkpoint near the border with the Gaza Strip as part of a joint investigation.

The Palestinians have detained seven members of a rogue militant group, the Popular Resistance Committees (search), and have briefed the U.S. team on the questioning of the detainees, but a senior U.S official said cooperation from Palestinian security officials was mixed.

Also Saturday, a Palestinian delegation was preparing to travel to the United States on Sunday to meet with officials about the fence Israel is building around the West Bank to keep Palestinian suicide bombers out of the country, Israel Radio reported.

The Palestinians also will discuss with Bush administration officials and congressmen a recent far-reaching peace proposal negotiated by Israeli and Palestinian officials, but which neither leadership has committed to.

In Saturday's pre-dawn fighting in Gaza, Israeli troops fired on armed Hamas militants who were planting explosives along paths traveled by Israeli tanks in the Rafah refugee camp, the army and Hamas members said.

Tariq Abu Hussein, 39, a well-known local field commander of the Hamas military wing, and another Hamas militant were killed. At least 10 people were wounded.

Several bystanders who had come to evacuate casualties in their car were fired on by a tank and machine guns, witnesses said. A woman in the car, Widad Ajrami, 28, was killed and her husband and a brother-in-law were wounded, said a relative, Mohammed Ajrami. The car was riddled with bullets and its seats were smeared with blood and littered with shards of glass.

An army spokeswoman said soldiers only shot at armed men and denied reports that troops fired a tank shell.

For more than a week, Israeli troops backed by attack helicopters and tanks have fought pitched battles with Palestinian gunmen in Rafah, an operation meant to uncover tunnels used by Palestinians to smuggle weapons under the Egyptian border.

So far, 14 Palestinians — including two children and a female bystander — have been killed since the operation began. Troops have uncovered and blown up three smuggling tunnels.

At the funeral for the three Palestinians killed Saturday, a Hamas militant wearing a black ski mask fired his assault rifle into the air in front of 5,000 mourners and vowed revenge for Hussein's death.

"We promise his soul that our fighters will teach the enemy a lesson they will never forget," he said.

In the West Bank town of Tulkarem, Israeli troops fired at several hundred stone-throwing youths — many of them students getting out of class for the day — killing a 17-year-old Palestinian and wounding five others, doctors said.

At least one fire bomb was hurled from the crowd, witnesses said. The army said troops fired after the fire bomb was thrown, hitting one person.

In the northern West Bank (search), a Palestinian gunman opened fire on an Israeli car Saturday evening, lightly injuring an Arab Israeli man, according to Israel Radio.

Elsewhere in the West Bank, three Palestinian militants were wounded by gunfire during another clash with Israeli troops.

Israel's military has said it launched its new Gaza (search) operation — the biggest in the coastal strip of territory in about six months — after it received intelligence warnings that Palestinians might be trying to smuggle more advanced weapons, like anti-aircraft missiles, through the cross-border tunnels. Until now, the tunnels have been used to smuggle lighter weapons, like assault rifles and ammunition, from Egypt, the army says.

Throughout much of the last three years of fighting, Rafah and its refugee camp have been a daily battleground, with gunmen attacking army outposts along the border and clashing with soldiers searching for the hidden underground tunnels.

The U.N. Relief and Works Agency, which aids Palestinian refugees, said earlier this week that 114 homes had been destroyed at the start of the operation, leaving 1,240 people homeless. The army said about 30 buildings were knocked down.

The human rights group Amnesty International called the destruction a "war crime."