Strikes were recorded in at least three locations in Gaza, Palestinian security sources and eyewitnesses said, with Hamas bases struck near the southern city of Rafah and Gaza City, as well as open land southeast of Gaza City.
The Palestinian health ministry said there were no immediate reports of injuries, but an AFP photographer in Gaza saw at least one man bleeding being taken for treatment from a house near the base.
The Israeli army said the strikes were in "response to projectile fire that hit near the Sha'ar Hanegev Regional Council."
"Two (Israeli) aircrafts targeted two military infrastructures belong to the Hamas terrorist organisation," it added.
That rocket, fired a few hours earlier, landed in an open area close to Israeli border communities without causing any injuries.
The rocket was claimed by a previously unheard of Salafist group.
Israel and Hamas have fought three wars since 2008.
Since the last one in 2014, a fragile ceasefire has been observed along the largely closed border.
Missiles and rockets are periodically fired at Israel, generally by hardline Islamist groups opposed to Hamas.
But Israel holds Hamas responsible for all rocket fire from Gaza regardless of who carried it out.
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