An Israeli airstrike barrage killed four unsuspecting boys on a beach in Gaza Wednesday, according to witnesses, the latest grim fatalities in the aerial battle between Israel and the militant group Hamas.

The victims, between the ages of 9 and 11, had the same last name and were described to be two brothers and two cousins, Palestinian authorities said. Since most of the foreign media are staying at a hotel that was situated close to where the military strike landed, the blast and its aftermath was witnessed by some of them, including ABC News.

After one of the boys in the group got killed on impact from the first shell, the four remaining boys were witnessed running across the beach, witnesses and Gaza medical sources said. A second shell struck, killing three more boys, the witnesses told ABC News. The fifth boy remains in critical condition, the medical officials said.

The four boys were identified by Gaza health officials as Ismail Bakr, 9, Ahed and Zakaria Bakr, both 10, and Mohammed Bakr, who was 11. Additionally, seven others - adults and children - were wounded in the strike, Ashraf Al Kedra, a Palestinian doctor, told the Associated Press.

The circumstances of the beach attack will be investigated, a statement by the Israel Defense Forces said. "The IDF has no intention of harming civilians dragged by Hamas into the reality of urban combat. We are carefully investigating the incident in question," the statement said. "Based on preliminary results, the target of this strike was Hamas terrorist operatives. The reported civilian causalities from this strike are a tragic outcome."

The on-going nine day conflict between Israel and Hamas has killed more than 200 Palestinians, and left one Israeli dead.

Meanwhile, Israel announced a unilateral "humanitarian truce" for five hours Thursday to allow Gaza residents to stock up on food and other supplies and let aid reach civilians. The pause in fighting was requested by the United Nations.