Hamas has said that a senior commander of its military wing was killed in an Israeli air strike.
Israeli warplanes launched missiles against five Hamas targets, in response to a rocket attack on the Israeli coastal city of Ashkelon.
Friday's strike against Ashkelon caused damage but no injuries.
The violence came after weeks of relative calm, raising concerns of new escalation.
Hamas identified the dead man as Issa Batran, a commander of its military wing in central Gaza and a rocket maker. Hamas said eight of its supporters and three civilians were also wounded.
Hamas has been firing crude rockets at Israel for a decade, but largely held its fire since Israel's military offensive against Gaza 19 months ago.