Palestinian terrorists in the Gaza Strip fired some 20 rockets and mortars into southern Israel since midnight Sunday, injuring four people, with 43 others suffering from shock.Palestinian groups in the Strip reportedly agreed to stop their attacks if Israel halted its own attacks on Gaza, although two rockets were fired shortly after news of the intention to calm the situation surfaced.Ben Hartman and Yaakov Lappin contributed to this report.The Palestinian attacks mark the third straight day of escalations. Over the weekend, terrorists fired some 100 rockets into the South, leaving three people injured in Sderot.The Iron Dome missile-defense system intercepted two rockets near Ashkelon and later in the day, intercepted two Grad rockets fired toward Ofakim. One Grad rocket hit an abandoned residential home in Netivot earlier Monday, causing significant damage to the building. Another, later in the day, caused damage in Netivot's industrial area.The Israeli Air Force struck three targets in the Gaza Strip overnight Sunday. The warplanes targeted a tunnel used for terrorist purposes and a weapons storage facility in the northern Gaza Strip, and a rocket-launching site in the south of the Strip, the IDF Spokesman's Office said in a statement. The airstrikes, the IDF said, were in response to the rocket and mortar fire into Israel.<Just before Monday morning's rocket barrage, Strategic Affairs Minister Moshe Ya'alon said that he had no faith the cease-fire would hold much longer, suggesting he expected rocket fire from the Gaza Strip to resume shortly. Senior Israeli leaders commented on the state of affairs in the South, warning of potential IDF repercussions for continued rocket attacks. Defense Minister Ehud Barak said Saturday that “if we are forced to go back into Gaza in order to deal Hamas a [serious] blow and restore security for all of Israel’s citizens, then we will not hesitate to do so." “It is Hamas that will pay the price; a price that will be painful,” he said.Prime Minister Binyamin Netanyahu also warned, “We are prepared to intensify our response,” speaking at Sunday’s cabinet meeting. “The world needs to understand that Israel will not sit idly by in the face of attempts to attack us,” the prime minister said.The prime minister held consultations with military and security heads, including Barak and IDF Chief of Staff Lt.-Gen. Benny Gantz over the state of affairs in the South.