IAF aircraft bombed the Islamic University and government compound in Gaza City early Monday morning, both centers of Hamas power. Witnesses saw fire and smoke at the university, counting six separate air strikes there just after midnight. Two laboratories in the university, which served as research and development centers for Hamas's military wing, were targeted. The development of explosives was done under the auspices of university professors. University buildings were also used for meetings of senior Hamas officials. The IDF said rockets and explosives were stored in the buildings. For the first time overnight Sunday, the IDF Navy began to participate in the operations and bombed targets across the Gaza Strip. Among them were smuggling tunnels, weapons' manufacturing plants and weapon warehouses, as well as boats used by Palestinian terrorists. Other targets were a guest palace used by the Hamas government, and the house next to Hamas Prime Minister Ismail Haniyeh's home in a refugee camp next to Gaza City. He was not home, as Hamas leaders have gone into hiding. Seven Palestinians were killed in the late night strikes, according to Israel Radio. A total of 307 Palestinians were reported to have been killed in the IDF operation. Also overnight Sunday, IDF Chief of General Staff Lt.-Gen. Gabi Ashkenazi spoke with chiefs of staff from around the world to explain Israel's ongoing operation against Hamas in the Gaza Strip. Several hours after Operation Cast Lead began, Ashkenazi called the chairman of the US Joint Chiefs of Staff, Admiral Michael Mullen, to explain to him the objectives of the operation. Earlier this year, Mullen visited the Gaza border with Ashkenazi during one of his trips to Israel. On Sunday, Israel continued to pound the Gaza Strip, striking at 40 tunnels along the Philadelphi Corridor as the defense establishment received approval to call up thousands of reservists and considered sending ground forces deep into Gaza to hunt down and destroy Hamas infrastructure. Forces were placed on high alert across the country as Military Intelligence warned of a Hamas "showcase" terror attack - including the possible abduction of a soldier - to avenge the massive and unprecedented bombardment of Gaza, the killing of some 350 Palestinians, and the wounding of some 1450 people since Saturday. The majority of the Palestinians killed in the raids were policemen and gunmen belonging to Izaddin Kassam, human rights activists and medical sources said Sunday. Hamas, officials warned, had dug tunnels under the crossings between Israel and Gaza to be used in explosives attacks. Throughout the day, forces continued to amass along the Gaza border. IDF artillery batteries were deployed outside Gaza for the first time in a year, alongside tanks and infantry troops. Defense officials would not specify when and if the ground operation would be launched but stressed that Israel would not hesitate to expand and deepen its operations as necessary. Some 30 Kassam rockets struck Israel throughout the day, with two hitting as far north as Ashdod, some 40 kilometers from Gaza. Two people were lightly wounded in the attacks. Defense officials were pleased by the dramatic drop in rocket fire - on Saturday over 90 rockets and mortars pounded the South - and said it was likely the combination of a number of factors: Hamas has been significantly weakened due to the non-stop air strikes and its leadership had been hit and had difficulty communicating since many Hamas leaders were underground. There was also the possibility that Hamas was "playing with Israel" and planned to launch barrages in the coming days, they said. "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 senior official. Officials added that the change in weather - rainstorms are expected throughout the country starting Monday - will impair the air force's ability to operate over Gaza and could pave the way for Hamas to escalate the rocket fire into Israel. The non-stop bombing of Gaza, officials said, made it difficult for Hamas to set up and fire the launchers. "When the weather changes, Hamas will have opportunities that it hasn't had up until now," another official said. The Home Front Command said it would enforce a strict defense policy in communities within a 30-km. range of Gaza and that schools would remain closed until further notice. Residents in cities 30-40 km. away from Gaza - such as Beersheba, Yavne and Gedera - were instructed to always be within one minute of a secure room. Shin Bet (Israel Security Agency) chief Yuval Diskin told the cabinet Sunday that Hamas was in shock, but was capable of and preparing to carry out attacks that would change the "picture" in the fighting with Israel. Senior defense officials told The Jerusalem Post that it was possible that Hamas would fire rockets into Beersheba in the coming days to prove to Israel that it was capable of penetrating deep into the home front. In the most dramatic attacks Sunday, fighter jets struck 40 smuggling tunnels connecting the Palestinian and Egyptian sides of Rafah, a Gaza Strip border town which serves as the main conduit for weapons, explosives, foreign military equipment and consumer goods into Gaza. The IDF said that the bombing took less than four minutes. Since the beginning of the Operation Cast Lead, 230 sorties were flown by fighter jets, 56 sorties by attack helicopter and 23 by other aircraft. Sunday's blasts made the ground shake several kilometers away and sent black smoke high into the sky. Earlier in the day, IAF jets dropped three bombs on one of Hamas's main security compounds in Gaza City, including a prison building. The bombing set free dozens of prisoners, who rushed out from their cells carrying bags of clothes and blankets with them as they scrambled over rubble, fleeing Hamas police. One man remained pinned under the rubble, his face smeared with white dust and blood, shouting: "Wait for me! Pull me out!" Gaza's nine hospitals were overwhelmed with casualties. Dr. Moawiya Hassanain, who keeps a record for the Gaza Health Ministry, said more than 290 people were killed over two days and more than 800 wounded. On Sunday, 25 unclaimed bodies still lay in the morgue of Gaza's largest hospital, Shifa, their faces disfigured beyond recognition. In Rafah, residents held a mass funeral for 14 people, including two brothers and a father and son, all of them members of the Hamas security forces. Defense Minister Ehud Barak decided Sunday night to allow the transfer of 100 trucks into the Gaza Strip carrying donations from Jordan, Turkey and international organizations. The trucks will transfer medical supplies, basic foods and 10 ambulances. Defense officials said that Barak's decision to permit the convoy to enter Gaza had been made to help show the civilians in Gaza that Israel's fight was with Hamas and not them. Barak also asked and received approval from the cabinet and the Foreign Affairs and Defense Committee on Sunday to issue emergency call-up orders for some 6,500 reservists. Officials said that already before the operation, Barak secretly received approval from Prime Minister Ehud Olmert to call up several hundred reservists from the Home Front Command, the IAF and Special Forces, and that the new orders would not be issued immediately. At least 1,500 of the call-up orders will go to additional soldiers from the Home Front Command. According to a Ma'agar Mohot poll broadcast Sunday night on Channel 10, 81 percent of Israelis support the war and only 17% oppose it. However, 63% do not believe that Israel will succeed in stopping rocket attacks from the Gaza Strip, while 17% think Israel will. The poll found that support for Labor had increased by 50% since the assault began and that Kadima had also been boosted. While in the past polls had predicted more than half the 120 MKs of the next Knesset would be from parties to the Right of Kadima, the new poll predicted that 61 MKs would be from Kadima and parties further to the Left. If the election were held today, the poll indicated, Likud would win 30 seats, Kadima 28 and Labor 16. Gil Hoffman and Jpost.com staff contributed to this report.