Hamas and most other factions in Gaza have announced a new ceasefire after a day of fierce fighting.
The Israeli army pounded Gaza with 45 rockets and mortars over a three-hour period, killing five Palestinians and wounding dozens in retaliation to a Hamas strike on an Israeli school bus.
Israel also said its interceptor missiles brought down two rockets fired from Gaza in the direction of the city of Ashkelon.
Hamas says its attack on the bus was in retaliation for an Israeli strike on Saturday in which three Palestinian militants were killed. An Israeli teenager was seriously wounded and the driver was injured. Some 40 pupils had got off the bus at the previous stop.
The attacks followed a relative lull in cross-border fire after a sudden rise in violence last month which claimed at least 16 Palestinian lives.