Israel has intensified its assault on Gaza, as Palestinian militants continue to fire rockets into Israel on the fifth day of hostilities.
Israel's military said air and ground forces were involved in attacks on Friday but had not entered Gaza.
Video from Gaza City showed the night sky lit up by explosions from Israeli artillery, gunboats and air strikes.
Some 119 people have been killed in Gaza and eight have died in Israel since fighting began on Monday.
Meanwhile, Jewish and Israeli-Arab mobs have been fighting within Israel, prompting its president to warn of civil war.
Defence Minister Benny Gantz ordered a "massive reinforcement" of security forces to suppress the internal unrest that has seen more than 400 people arrested.
Police say Israeli Arabs have been responsible for most of the trouble and reject the accusation that they are standing by while gangs of Jewish youths target Arab homes.
