An explosion Saturday destroyed a black Mercedes in the Gaza Strip, killing four people and injuring one. Palestinian officials claimed it came under Israeli tank fire.

Tanks and helicopters were in the general area of the blast in al-Zahra (search), on the outskirts of Gaza City not far from the Jewish settlement of Netzarim (search). But, the Israeli army said it had not fired at any car and its soldiers were not near the explosion.

A military source said an army helicopter had fired machine-gun warning shots earlier near the area after Palestinian gunmen fired at soldiers.

The Palestinian Public Security (search) directorate in Gaza, after first saying the car was destroyed in an Apache helicopter missile strike, issued a statement saying further investigation revealed the damage was from a tank shell.

Palestinian witnesses said the driver of a passing motorcycle was among the victims, but it was unclear whether the motorcyclist was injured or among the dead.

Ibrahim al-Musder, the director of the Al-Aqsa Martyrs Hospital (search) in nearby Deir el-Balah, said the remains of four people were brought in along with one injured person.

"The bodies of the people killed arrived in very bad shape, which makes it hard for the moment to identify them," al-Musder said.

The Hamas militant group claimed in a call to The Associated Press in Gaza that a group of Hamas fighters had ambushed an Israeli undercover unit operating near Netzarim, beginning the day's clashes.

The Israeli army said it had no information about any ambush. Earlier Saturday, the army said Palestinians had fired two anti-tank missiles and sprayed machine gun fire at Israeli soldiers near Netzarim, but that nobody had been injured.

Later, Palestinian medical sources said a medical worker had been wounded by a gunshot in the stomach.

been injured.

Later, Palestinian medical sources said a medical worker was shot in the stomach and wounded.