The three raided sites are located in the east, north and northwest, and one of them is the training site of the Qassam Brigades, the military wing of the Islamic resistance movement Hamas east of Gaza city, Xinhua news agency quoted a source as saying.
The Israeli air force attacked the Gaza Strip in response to the firing of a mortar shell in western Negev overnight on Wednesday.
The Israeli Defence Forces (IDF) released a statement saying that "the IDF holds Hamas responsible for what happens in the Gaza Strip and will continue to act sternly to ensure the safety of southern communities."
On August 21, the Israeli air force launched five raids on the Gaza Strip in response to the launch of a rocket from Gaza into southern Israel, without causing casualties.
