Conflicting reports emerged Sunday regarding the fate of top Hamas military commander Ahmed Ja'abri, who may have been killed in one of the hundreds of Israeli air strikes against Hamas infrastructure in the Gaza Strip. Since Operation Cast Lead began on Saturday, the air force has flown over 300 sorties over the Strip, bombing close to 280 different targets. Palestinian and Israeli sources said that Ja'abri, the overall commander of Hamas's armed wing, Izaddin Kassam, may have been killed in an air strike on a mosque which he frequented. Sources close to Hamas in the Gaza Strip said they could neither confirm nor deny the report. They said that the bodies of many of the victims had yet to be identified and that several bodies were still under the rubbles of demolished buildings. Defense officials said that at least 50 percent of Hamas's underground rocket launchers had been bombed during the air campaign, as well as a significant number of weapons warehouses. In addition, almost all of the Hamas bases and headquarters in the Gaza Strip were completely destroyed. On Sunday, IAF aircraft bombed a top Hamas security installation, a mosque, a TV station and dozens of other targets. But despite the bombings and the relatively low number of Kassam rockets fired into Israel throughout the day - some 30 in comparison to the earlier predictions of over 100 - senior officials said that Hamas was still capable of firing barrages of rockets into Israel. "Hamas's operational capabilities were damaged, but the group still has underground launchers as well as the capability to launch attacks along the security fence and into Israel," said one official. Officials said that Hamas was believed to still have thousands of Kassam rockets as well as a significant number of Grad-model Katyushas. Top officers would not rule out the possibility that Hamas may also have rockets with ranges greater that 40 kilometers. Hamas is also believed to have advanced anti-tank missiles as well as a number of shoulder-to-air missiles capable of downing Israeli aircraft. The majority of the Palestinians killed in the IDF air raids that began Saturday were policemen and militiamen belonging to Izaddin Kassam, human rights activists and medical sources said Sunday. They revealed that about 160 blue-uniformed policemen were killed in the first day of the operation. Most of the cadets were attending a graduation ceremony at the main police headquarters in Gaza City on Saturday. The IDF said that in total, over 280 Palestinians were killed, most of them Hamas operatives. Among the victims: Tawkif Jaber, the director-general of the Hamas-run "civil" police force in the Gaza Strip, and Ismail Ja'bari, commander of one of Hamas's most-feared security forces. The two are the most senior Hamas officials who are known to have been killed since the beginning of the IDF operation. A human rights activist estimated that so far at least 60 civilians had been killed, including nine children under the age of 14 and 20 women. Another human rights activist said he knew about "fewer than 45" civilian casualties. By Sunday night, the Palestinians reported that about 300 people had been killed and 1000 wounded since the beginning of the operation. Palestinian journalists in Gaza City said they were facing many difficulties in collecting information about the casualties because of restrictions imposed by Hamas and because many of the victims' relatives had buried the bodies quickly.