Gaza- Nine Palestinian have been killed in a series of Israeli air raids on the Gaza Strip, Medics said today. The armed wing of the Palestinian group Hamas says six of its fighters died in a single strike near Rafah in the south. Three others died in separate Israeli air strikes. Tensions in the region are high following the murder of Palestinian teenager Mohammed Abu Khdair. Police believe there was a nationalist motive to his killing, and have arrested six Jewish suspects. The death followed the murder of three Israeli teenagers, whose bodies were found a week ago. Emergency services in Gaza confirmed only two deaths from the air strike in Rafah but four others are believed to be buried under the collapsed site. A seventh victim was reported killed in another attack. Earlier, two other Palestinian militants were killed in a separate air attack near a refugee camp in central Gaza. The Israeli military said the strikes were in response to rocket attacks against southern Israel and targeted "terror" sites and concealed rocket launchers. But Hamas's military wing, the Izz al-Din al-Qassam Brigades, vowed that Israel would pay "a tremendous price." There have been days of tit-for-tat strikes across the Gaza border. Israel has arrested hundreds of members of Hamas during its search for the kidnappers of the three Israeli teenagers. That may help to explain the sudden intensification of rocket fire from Gaza, he says.