A Palestinian sniper opened fire on an IDF unit guarding workers carrying out maintenance work near the Gaza border on Wednesday, seriously wounding a soldier from the Beduin Reconnaissance Battalion.The soldier was evacuated to hospital, where doctors said he was in stable condition.The sniper’s organizational affiliation was unknown.The IDF responded by directing an air strike and tank shells at Hamas positions in southern Gaza, killing a member of its military wing.Palestinian media reported that the return fire killed a Hamas field commander, Tayseer Asmairi.“This is a severe incident – the second within a week – in which quiet has been callously violated,” the army said.“The IDF will continue to respond to every attempt to harm Israeli soldiers and civilians. Hamas is responsible for safeguarding the quiet in the Strip.”Security sources later said they doubted the cross-border shooting was a planned assault.Farmers in the Eshkol and Sdot Negev regions were ordered to halt work within a kilometer of the security fence until further notice and to stay away from the border.Police sealed off roads around Kissufim and Kibbutz Ein Hashlosha.“We are ready for any eventuality,” IDF Chief of Staff Lt.- Gen. Benny Gantz said hours after the attack, speaking at the Calcalist Conference.“This instability is a set feature of life for the IDF and for Israel on its borders. We have no intention of letting these challenges pass without a response. We responded on the spot.” He stressed that soldiers were attacked as they stood in Israeli territory.Hamas’s armed wing, Izzadin Kassam, warned Israel against “continuing to violate” the Egyptian-brokered cease-fire that was reached in August, saying Israel would be the first to be burned by its fire.Referring to Wednesday’s incident, the group said this was a “dangerous violation and a crossing of all redlines, as well as playing with fire.”The group said in a statement issued in the Gaza Strip, “The enemy alone bears the responsibility of the repercussions of its uncalculated actions.”The Palestinian factions in the Gaza Strip were studying the incident to decide their response, the Hamas group said, claiming that the killing and other Israeli measures in the West Bank and Jerusalem were part of a “Zionist-Western plot in collusion with some traitors and hypocrites.“It seems that this murderous enemy has not learned the hard lessons it was dealt by the resistance in the past,” Izzadin Kassam added. “The enemy thinks that our people and the resistance are tired or exhausted after the last war.”Another group in the Gaza Strip, the Popular Resistance Movement, warned that Israel would pay a heavy price for killing Asamiri, one of its top activists.He is the second Gazan to be killed by the IDF since Operation Protective Edge ended.Israel will respond strongly and with determination against all attacks in the South, Prime Minister Benjamin Netanyahu said, commenting on the IDF response.“We will respond with force every time there is an attempt to disturb the quiet that was attained in the South after Operation Protective Edge,” Netanyahu said.Intelligence Minister Yuval Steinitz said Israel would not accept a deterioration on the border.“Hamas needs to understand that if it continues to undermine the security situation on the Gaza border, it risks a harsh Israeli response, which could turn into a comprehensive military campaign to demolish its government and military infrastructure,” he said.Meanwhile, the UN’s deputy Mideast envoy, James Rawley, issued a statement urging all parties to maintain and reinforce the August 26 cease-fire that put an end to Operation Protective Edge.Rawley “is deeply concerned by reports of exchange of fire between Palestinian militants and the IDF in the southern Gaza Strip today, which resulted in casualties on both sides. This follows a series of armed incidents since the end of November,” the statement read.On Friday, a Gazan rocket triggered warning sirens in the Eshkol region, before exploding in an agricultural field. It failed to cause injuries, but damaged the field, before being collected by an Israel Police bomb squad. It was the third time Palestinians had fired a rocket into Israel since the truce with Hamas went into effect.The Israel Air Force struck a Hamas cement factory in the southern Gaza Strip overnight between Friday and Saturday in response to the rocket, targeting a site used to reconstruct Hamas’s network of tunnels.