RAMALLAH – Israeli airstrikes killed three Palestinians and wounded several others early Wednesday on Gaza Strip in a new surge of cross-border violence. Palestinian medical sources said that the three were killed in separate attacks that took place in the southern Gaza town of Rafah and the northern town of Beit Lahya, putting the death toll to four since Tuesday. The sources said that the three were members Izz El-Din Al-Qassam Brigades, the armed wing of Hamas movement and the Popular Resistance Committees (PRC), a group with close ties to Hamas. Palestinian security sources said that the Hamas security forces were ordered to evacuate their facilities in Gaza Strip for fear they would become targets of Israeli air strikes. Crossings between Gaza and Israel were shut down following the exchanges of fire in the area. The spokesman of Israeli army confirmed the attacks saying that the Israeli forces opened fire against rocket-launching squads in Gaza Strip. The Israeli escalation came after Palestinian armed groups fired 60 rockets and mortar shells into southern Israel Wednesday morning. Israeli medical sources said that three foreign workers at the Eshkol Regional Council were injured on in an ongoing rocket attack on southern Israel. The sources said that two of the three sustained serious wounds and one sustained light wounds. The Israeli army's Home Front command instructed residents living within 10 km of Gaza to remain indoors and take shelter. The Iron Dome missile defense system intercepted seven rockets heading toward Ashkelon, the Israeli Army Radio said. Hamas' military wing and the Popular Resistance Committees have both claimed responsibility for the rocket attack. “These holy missions come in response to the repeated, continuous crimes of the enemy against our people, which killed four and injured 10 in the past 48 hours,” the armed groups said in statement. The attacks seem to be a resumption of the cross-border violence that started early this week, which halted temporarily Tuesday due to the landmark visit by Qatar's Emir Sheikh Hamad Bin Khalifa Al-Thani. Responding to the barrage of rockets, Israeli Defense Minister Ehud Barak said that the army will take all necessary action to return the quiet to the south. “If we need a ground operation there will be a ground operation. We will do whatever necessary to stop this wave (of violence),” Barak said during an interview with Israel Radio. The defense minister also said he does not see the recent escalation in the south as related to the Qatari Emir's visit to Gaza. Asked whether negotiations with Hamas might be productive, Barak said the organization is an enemy with whom Israel cannot communicate. Fawzi Barhoum, a Gaza-based Hamas' spokesman, said that his movement was unfazed by the retaliation. “Israel is embarrassed by the visit in Gaza of the Emir of Qatar, and his successful breaking of the political and economic blockade of the Strip,” Barhoum said.