Israeli air strike kills 4 in Gaza

Violence in Gaza continued on Monday as an Israeli air strike killed four Palestinian militants, Palestinian medical and security officials said.

Islamic Jihad, a militant group that has fired numerous rockets into Israel, said its members were killed in the attack near the Jebaliya refugee camp in northern Gaza.

Israel's army confirmed the air strike as part of its ramped-up military response to an increasing number of Kassam rocket attacks on southern Israel.

The armed faction of the ruling Hamas party broadcast a radio warning on Monday, advising its members to stop using cellphones to avoid being tracked by Israeli intelligence.

The message also warned against travelling in groups or in vehicles because Israeli warplanes are "in skies all the time."