Israel bombed areas of southern Gaza where it had told Palestinians to flee to ahead of an expected ground invasion, killing dozens of people on Tuesday in attacks it says are targeted at Hamas militants that rule the besieged territory. The Hamas-run Health Ministry in the Gaza Strip said at least 500 people were killed in an explosion Tuesday that it said was caused by an Israeli airstrike on a Gaza City Hospital. If confirmed, the attack on the al-Ahli Hospital in Gaza City would be by far the deadliest Israeli airstrike in five wars fought since 2008.