JERUSALEM, Feb. 4 (JTA) — Israel has been plunged into deep mourning in the wake of what is the country’s worst air force disaster. At least 70 Israeli soldiers were killed Tuesday night when two army helicopters en route to the southern Lebanon security zone crashed in bad weather over an Israeli farming community in northern Israel. According to initial reports, there were no survivors among the troops. No residents of the community, Moshav Sha’ar Yishuv, were hurt. “Tonight we suffered a horrible tragedy,” Prime Minister Benjamin Netanyahu said. “We lost dozens of our best sons, brave soldiers in the Israel Defense Forces,” the premier said. “We are deeply grateful to the soldiers who work day and night to protect us and defend the State of Israel. I pray and hope that we will not know such tragedies ever again.” The head of the IDF northern command, Maj. Gen. Amiram Levine, confirmed the extensive casualties during an initial briefing for reporters. Israel has maintained troops in the 9-mile-wide security zone since 1985 to prevent cross-border terror attacks and to prevent the Islamic fundamentalist Hezbollah movement from firing Katyusha rockets at northern Israeli communities. Heavy fire was exchanged this week between Israeli and Hezbollah forces in southern Lebanon. The crash took place amid an ongoing national debate about the wisdom of a continued presence in southern Lebanon. According to initial reports, the two helicopters crashed about 7 p.m. over Moshav Sha’ar Yishuv, located near Kiryat Shmona. Snow had been falling Tuesday in northern Israel, and there was heavy fog at the time. One of the helicopters crashed into a vacant house on the moshav. The helicopters were bearing large amounts of ammunition, and the impact set off a series of fiery explosions. Firefighters, rescue crews and security forces rushed to the area, which was declared a closed military zone. Netanyahu canceled a trip to Jordan scheduled for Wednesday because of the air disaster. King Hussein expressed his condolences to Israel, as did Palestinian Authority leader Yasser Arafat. President Ezer Weizman, a veteran pilot, said he believed it was Israel’s worst air disaster. Defense Minister Yitzhak Mordechai issued a statement expressing shock and grief over the tragedy. He vowed that the IDF would fully investigate the cause of the crash. Eyewitnesses described seeing massive explosions lighting up the night sky. “It was near the guest cabins. We heard two explosions. I went outside to see what they were, and we saw a helicopter falling on one of them,” Sylvia Cohan, a resident of Moshav Sha’ar Yishuv, told Israel Radio. “Everything exploded. It was total chaos.” “I heard helicopters overhead, and looked towards the valley when I saw a huge explosion,” said Smadar Edelin, an eyewitness who saw the helicopters from the Hermon field school, which overlooks the community where the crash took place. “At first, I thought it was a Katyusha rocket attack, which we are used to. Then I heard a smaller explosion and saw a helicopter flying low over the ground, and then it exploded.” Firefighters said they arrived at the scene minutes after the crash, but could not begin their work because of the intensity of the flames.