Violence has flared between Israel and Palestinian militants in Gaza, a day after seven militants and an Israeli soldier were killed during an undercover Israeli operation in Gaza.
Militants fired 200 rockets and mortars at Israel on Monday. One hit an empty bus, seriously injuring a man nearby.
Israel responded with strikes on what it said were military targets belonging to Hamas and Islamic Jihad.
Three Palestinians, two of them reportedly militants, were killed.
Israeli Prime Minister Benjamin Netanyahu earlier cut short his visit to Paris for events to mark the 100th anniversary of the end of World War One and returned to Israel to consult with his security chiefs.
A Hamas commander and an Israeli soldier were among the dead on Sunday.
Palestinians said an Israeli unit travelling in a civilian vehicle had killed the Hamas commander.