Two Palestinians have been killed in air strikes on the Gaza Strip after they had clashed with Israeli troops crossing into the territory, medical sources say. Both strikes took place on Sunday around the northern town of Beit Hanoun where fighters were firing mortar shells at an Israeli tank and several military vehicles which had crossed the border, witnesses and security sources said. The flare-up provoked threats of revenge from the Ezzedine al-Qassam Brigades, the armed wing of the ruling Hamas movement, and a pledge from Israeli Prime Minister Binyamin Netanyahu that there would be no immunity for those firing on Israeli forces. The first strike hit north of Beit Hanoun, critically wounding four Qassam Brigades fighters, one of whom later died of his injuries, medics and the group said. As the clashes continued, Israel launched a second air strike east of the town, killing a fighter from the Popular Resistance Committees (PRC) and critically wounding another man, the same sources said. The Qassam Brigades confirmed that one of its local commanders and a PRC fighter had been killed. The Israeli military said that both strikes had targeted "a rocket launching squad". "The squad was targeted in response to mortar shell fire at a routine IDF [army] patrol in the area, near the Israeli kibbutz of Nir Am," a statement said of the first strike. An identical statement was issued following the second strike.