Exchanges of fire mar 3-hour truce in Gaza

JERUSALEM (CNN) -- A planned three-hour lull in Israel's assault on Gaza was marred by sporadic attacks by Hamas militants and retaliatory fire from Israeli forces.

Flames rise into the sky after an Israeli airstrike Wednesday night in Rafa, on the Gaza-Egypt border.

The suspension of the campaign from 1 p.m. until 4 p.m. (6 a.m. to 9 a.m. ET) was intended to allow residents of the Hamas-ruled Palestinian territory to receive food and medical supplies.

U.N. Relief and Works Agency spokesman Chris Gunness said a three-hour truce is not enough to alleviate the "deepening humanitarian crisis" in Gaza.

"We are feeding 750,000 (people) on a permanent basis," Gunness said. "More than three hours a day are needed for that."

A three-hour truce is scheduled to take place every other day, Israeli Defense Ministry spokesman Peter Lerner said.

"We need to build on this three-hour window; we need to expand that window and let it lead to a permanent cease-fire," Gunness said.

Israel said Wednesday that it "welcomes" a truce plan by Egypt and France and will continue its discussions with both countries about how to achieve a cease-fire in Gaza, an Israeli government spokesman told CNN.

Israel will send two envoys to Cairo, Egypt, in the coming days to discuss a Gaza truce plan, an Israeli foreign ministry official said Wednesday.

The envoys -- Defense Ministry official Amos Gilad and Shalom Turgeman, a political adviser to Israeli Prime Minister Ehud Olmert -- could head to Cairo as early as Thursday, the official said.

It is not clear whether Hamas, the Palestinian movement that governs Gaza, will send representatives to Cairo. Israel refuses to speak directly to Hamas, which it considers a terrorist organization, but it has negotiated with Hamas through Egypt in the past.

By Wednesday evening, 16 rockets had struck the Jewish state, according to the Israeli military. There was no immediate report of injuries.

At least 680 Palestinians have been killed and 3,000 wounded in Gaza since the campaign began on December 27, Palestinian medical officials said.

Nearly a third of the deaths and 45 percent of the injuries are women and children, according to the U.N.'s Office for the Coordination of Humanitarian Affairs. Seven Israeli soldiers and three civilians have been killed.

Israeli warplanes and helicopter gunships hit 30 targets in Gaza overnight, while land-based artillery and warships offshore fired at Palestinian fighters in support of Israeli ground troops, the Israel Defense Forces reported as the campaign entered its 12th day.

Tuesday was the bloodiest day of the Israeli ground offensive to date, when Israeli shelling struck a U.N. school in northern Gaza that was being used as a shelter by hundreds of civilians.

The Israeli military said Hamas militants were firing mortars from the school, prompting an artillery strike that killed at least 40 people and wounded dozens more. U.N. officials said there were no militants at the school.

"We are 99.9 percent certain that there were no militants. There were no militant activities in the school or in the school compound," said Gunness of the U.N. Relief and Works Agency.

The Palestine Red Crescent said five ambulances had been hit by Israeli forces, killing six people. The agency did not give a breakdown of paramedics and patients, and CNN was not able to independently verify these allegations.

The Israeli military said it was unaware of any such incidents.