For the second time in as many days, Palestinian fighters blew up an Israeli armored personnel carrier in the Gaza Strip on Wednesday, demolishing the vehicle and killing at least five Israeli soldiers, the Israeli military said Thursday morning.

Early Thursday morning, an Israeli AH-64 Apache helicopter fired at a group of Palestinians in the city of Rafah in the southern Gaza Strip, killing seven people and critically injuring two. Israeli military officials said the men were trying to plant a roadside bomb. A Palestinian security official said the men were simply standing in the street.

In the Wednesday attack, Palestinian guerrillas fired a rocket-propelled grenade at a convoy of three Israeli army vehicles at 6 p.m., according to a military spokesman, Capt. Jacob Dallal. The vehicles had stopped along a cleared corridor between Egypt and the Gaza Strip during a search for cross-border smuggling tunnels.

The grenade struck an armored personnel carrier loaded with explosive materials used to destroy tunnels, and the vehicle blew up, Dallal said. The blast killed an officer and four enlisted men and injured three other soldiers. The radical group Islamic Jihad asserted responsibility for the attack.

The incidents on Tuesday and Wednesday killed a total of 11 Israeli soldiers, making it the deadliest period for the Israeli military since April 9, 2002, when Palestinian gunmen killed 13 Israeli soldiers in the Jenin refugee camp in the West Bank.

At least 20 Palestinians have been killed since Tuesday and 172 have been injured, according to Palestinian military and medical officials.

Israeli officials did not immediately offer details about the attack Thursday in Rafah. "There's gunfights going on there, because we're trying to secure the area, and there's helicopter support," Dallal said.

The fighting began Tuesday when Israelis soldiers entered the Gaza City neighborhood of Zeitoun to search for and destroy weapons workshops. Six Israeli soldiers were killed when their vehicle, which also was packed with explosives, drove over a bomb planted by Palestinian guerrillas.

Egyptian intermediaries negotiated with various militant groups who had seized and displayed body parts of the Israelis, and by early Thursday Israel had retrieved the remains and withdrawn from Zeitoun.

Prime Minister Ariel Sharon of Israel has proposed a withdrawal from Gaza, where 7,500 Jewish settlers protected by thousands of troops live alongside 1.2 million Palestinians. But his plan has been in limbo since it was rejected by his Likud Party in a nonbinding referendum on May 2.

Political and military analysts in Israel said the soldiers' deaths would probably prompt calls for a review of military operations and equipment in Gaza and possibly encourage demands for an evacuation.

"There is a tactical problem people are talking about with thin-skinned armored vehicles full of explosives," said Mark Heller, a senior researcher at Tel Aviv University's Jaffee Center for Strategic Studies. "Politically, it's going to reignite the debate about the withdrawal and disengagement from Gaza and push people to look for different ways to proceed with this idea."

"You can make too much of two bombings in two days -- such things happen in war," said Martin Van Creveld, a military historian at Hebrew University. "But what it does show is that our attempt to hold Gaza is doomed and it always has been doomed, and the sooner we get out of that damn place the better."

In Gaza City on Wednesday, Israeli soldiers swept through the neighborhood of Zeitoun in a search for the remains of the six soldiers killed on Tuesday. Earlier, militants had proudly displayed the soldiers' body parts, including a head, in Gaza neighborhoods, and leaders of the groups had said they hoped to use the remains as bargaining chips to win the release of Palestinian militants being held by Israel.

Palestinian fighters engaged in gun battles with Israeli soldiers in Zeitoun, and Israel launched missile strikes that killed at least three Palestinians and injured about 50, Palestinian hospital officials said.

Before the handover of the remains, the International Committee of the Red Cross and Egyptian diplomats had contacted leaders of three Palestinian militant groups in Gaza and asked for help in recovering the remains, Red Cross and Palestinian officials said. The groups had each claimed to be holding body parts and had separate demands for their return.

Under Jewish law, a maimed body cannot be buried if any parts are missing. Late Wednesday, the families of the six soldiers had agreed to proceed with their funerals Thursday after consulting with the chief rabbi of the army, Brig. Gen. Israel Weiss, who advised them that it would be appropriate to do so.

The remains were returned, through the Egyptians, shortly after that.

Special correspondent Islam Abdulkarim in Gaza City contributed to this report.

Palestinians assist a man injured during clashes after Israeli soldiers entered the Gaza City neighborhood of Zeitoun.