The Israeli army Wednesday suspended a platoon commander on suspicion he emptied an ammunition clip into a 13-year-old Palestinian girl from close range after she had already collapsed under fire.

The officer was not charged but came under investigation after fellow soldiers said he engaged in an illegal practice known as "verifying a kill." The girl, who died, was shot 15 times, Palestinian doctors said.

In a nearby Palestinian refugee camp, meanwhile, a 10-year-old girl died Wednesday after being shot in the chest Tuesday while sitting at her desk in a school. The army said it fired at the camp in response to mortar fire from the area of the school. A U.N. aid agency denied the army claim, saying the camp was quiet at the time.

In other developments Wednesday, the army expanded its 2-week-old offensive in northern the Gaza Strip (search), with tanks moving deeper into the town of Beit Lahiya to try to stop Palestinian rocket fire at Israeli border towns.

Three militants were killed and seven Palestinians were wounded in the fighting, including four children between the ages of 5 and 16, hospital officials. One of the militants was killed by a missile strike, and two by a tank shell, witnesses said.

Israel's deputy defense minister, Zeev Boim, told Israel Army Radio that "the expansion of the operation proves we don't mean to let up" and that the number of rocket attacks has dropped.

In New York, U.N. Secretary-General Kofi Annan said Tuesday he was deeply troubled by the Israeli raid, and that he "grieves for the many children who have been killed or wounded in these operations."

The offensive was triggered by a Palestinian rocket attack Sept. 29 that killed two Israeli preschoolers. Since then, 102 Palestinians have been killed in northern Gaza, including 18 under the age of 16.

Despite the heavy army presence, two more Qassam rockets were fired Wednesday. They fell in empty areas, causing no injuries, but for the first time triggered an early warning system Israel installed in the Israeli border town of Sderot (search) last month. Sirens go off about 20 seconds before the rockets land.

In the West Bank, Israeli troops caught the commander of the Islamic militant group Hamas (search) in the city of Hebron, after surrounding his hideout. The Hamas chief, Emad Qawasmeh, is suspected of having dispatched a number of suicide bombers, including two who blew themselves up Aug. 31 on Israeli buses, killing 16 people.

Qawasmeh emerged from his hideout after soldiers ordered him to strip to his underwear, to ensure he was not armed. The house was demolished.

"Qawasmeh is a mass murderer whose hands are covered with the blood of many Israeli citizens," Israeli Defense Minister Shaul Mofaz told reporters during a tour of northern Israel.

In four years of fighting, about 400 Palestinians under age 16 have been killed by army fire, according to an Associated Press count. Many were killed while throwing stones at soldiers, others while in their homes, walking to school or observing clashes.

The shooting that prompted the suspension of the platoon commander took place on Oct. 5 near the Rafah refugee camp in southern Gaza. At the time, 13-year-old Iyman Hams was walking south of the camp. Her relatives said she was on her way to school when she was shot by soldiers from a nearby outpost.

The army said she had come close to the outpost, and was in a zone off-limits to Palestinians. Soldiers from the outpost suspected she was trying to plant a bomb after she dropped her school bag, and they opened fire.

Several soldiers from the outpost have since told Israeli media that after the girl collapsed, the platoon commander ran toward her and fired a volley from his automatic rifle from close range. Under open-fire regulations, soldiers may only shoot when their lives are in danger.

In discussing the case at parliament's Defense and Foreign Affairs Committee on Tuesday, several legislators used the term "verifying a kill."

Col. Eyal Eisenberg, an army commander in Gaza, told Israel Army Radio on Wednesday he has suspended the platoon commander pending the outcome of the investigation. Eisenberg said the investigation would be conducted quickly and that there would be no whitewash.

In the past four years, Israel's military police has investigated only a small number of soldiers in the killings of Palestinians. Investigations generally take months, and only a small number of soldiers have been put on trial.

In the Khan Younis (search) refugee camp in southern Gaza, a 10-year-old Palestinian girl, Ghadeer Mokheimer, died of injuries she sustained Tuesday while sitting at her desk in a U.N.-run elementary school.

The army said soldiers fired toward the U.N. compound after mortar shells were launched from there at Jewish settlements and army outposts. UNRWA denied the claim, saying the camp was quiet and that no mortars were fired from within U.N. grounds.

Peter Hansen, the UNRWA chief, said it was the second time in several weeks that an elementary student was killed while in school.

"That two young children have been shot and killed, sitting at their desks in UNRWA schools in the last month is horrific by anyone's standards. Schools should be havens of peace," he said in a statement.

Relations have been particularly tense between UNRWA and Israel after the military claimed earlier this month that a U.N. ambulance was used to transport a rocket. The army has since withdrawn the claim, saying it misinterpreted video footage taken from an unmanned Israeli aircraft, or drone.