Israeli warplanes struck multiple militant targets in the Gaza Strip early Thursday in response to earlier Palestinian rocket fire, but nobody was injured according to Palestinian security sources.

They said that the raids hit three training bases of the Izzadine al-Qassam brigades, the military wing of Hamas, in Gaza City and a fourth in the southern city of Khan Younis.

An Israeli military statement spoke only of three hits in total and did not give their location or identify the targets.

“Yesterday, June 3, 2015, two rockets were launched at southern Israel from the Gaza Strip,” it said adding that they fell on open ground near the southern city of Ashkelon and the town of Netivot. “No injuries were reported.”

“In response to this attack, the Israel Defense Forces struck three terror infrastructures in the Gaza Strip,” it said.

On Wednesday night police reported that three rockets were fired but that patrols were searching to find where they had fallen.

There was no immediate claim of responsibility, but Israel has a general policy of holding Hamas responsible for every rocket attack from the territory under its control, no matter which group actually launched it.

Israeli public radio said the latest volley could be related to internal Gaza infighting between the strip's Hamas rulers and its extremist opponents.

Hamas security forces on Tuesday shot dead a Salafist leader in Gaza City Tuesday during a confrontation.

The incident came as Hamas stepped up measures against militants belonging to Islamic extremist groups, some of whom are known as Salafists.

Salafists are Sunni Muslims who promote a strict lifestyle based on that of early “pious ancestors”. In Gaza they have made no secret of their disdain for Hamas over its observance of a tacit ceasefire with Israel and its failure to implement Islamic law.

Since last summer, when Israel and Hamas fought a deadly 50-day war in and around Gaza, there have been growing signs of internal unrest between Hamas security forces and extremist splinter groups.