Israeli helicopter gunships and tanks fired on Hizbullah positions Tuesday in southern Lebanon, killing one fighter, Lebanese security officials reported. Reports and Hizbullah indicated two Israeli soldiers were killed. Israeli military officials said it was Hizbullah snipers who started firing first, calling the shooting a "provocation." But the Lebanese security officials said the Israelis were the first to shoot, The AP reported. Witnesses in southern Lebanon said two Israeli helicopters fired two rockets at the Hizbullah positions near the border village of Aita Shaab, some 15 kilometers southeast of the coastal city of Tyre. Sources said Israeli tank opened fire on a Hizbullah position near Aita el-Shaab, killing a Hezbollah man. The Lebanese fighters returned fire at Israeli positions across the border. A Hizbullah statement said its dead fighter was killed by an Israeli tank shell that targeted an observation post at Hadab Aita near Aita el-Shaab. Israeli helicopters later attacked another observation post at nearby Ramia, but there were no casualties or damage, the statement added. Hizbullah vowed it would "chose the time and place for a deterrent response to make the enemy understand that aggression against the security and blood of our people would be very costly." The Israeli army on Tuesday was on its second day of alert along the northern border with Lebanon, after Hizbullah blamed Israel for assassinating an official in the group, Ghaleb Awali, on Monday. Hizbullah chief Hassan Nasrallah vowed from Beirut to mete out at all costs a "horrendous revenge" on the Jewish state for Awali's assassination. "Israel is fully responsible for comrade Awali's assassination, either directly by its Mossad secret service or by agents filling Lebanon from border-to-border and protected by high-ranking figures," Nasrallah said in eulogizing Awali. "I swear from this mosque to chop off their hands, each and all, irrespective of the costs and consequences," Nasrallah said as he led the funeral prayers for Awali. He said Mossad agents could have entered into Lebanon using forged U.S. or European passports. **PHOTO CAPTION*** Israeli soldiers stand next to their army vehicles as they wait on a stand-by position near the Israeli - Lebanese border in northern Israel, July 20, 2004. (REUTERS)