The Israeli military said one air strike had hit a high-rise building in al-Shati refugee camp in the northern Gaza Strip, describing the target as a Hamas urban warfare training facility with a tunnel underneath.
Health officials in Gaza said the building was empty, but two Palestiniansaged 15 and 16, among a crowd in a nearby public park, were killed. Around 10 other passers-by were wounded, the officials said. Nearby houses were damaged.
Israeli military spokesman Lieutenant-Colonel Jonathan Conricus said the military had warned people before the attack to leave the area. "We have no intention to harm anyone who is not a terrorist," he said.
Rocket warning sirens went off in the Israeli coastal city of Ashkelon, about 12 km (7 miles) from the enclave, further north than in recent attacks. A police spokesman said no hits had been recorded in the city.
Hamas stopped short of claiming responsibility for the rocket fire, but Barhoum earlier called it "an immediate response by the resistance to the escalation" by Israel and a deterrence to further Israeli attacks. "Bombardment for bombardment," he said.
The fighting began on Friday, when thousands of Palestinians gathered at the Israel-Gaza border area for weekly protests that have now entered their fourth month.
The Israeli military said Friday's protesters were throwing burning tyres, stones, explosive devices and fire bombs at its soldiers and that one of its officers was wounded by