A light aircraft piloted by an Israeli who took off without permission and failed to identify himself while flying over northern Israel caused a scare Saturday afternoon, prompting the Air Force to scramble military helicopters to investigate further. The incident ended peacefully and the choppers returned to base after the pilot was identified, the IDF said. "The Air Force registered an unknown aircraft on Saturday afternoon, flying over Israeli airspace. Air Force helicopters took off in the direction of the aircraft, and when the plane made contact, the helicopters returned to base," an IDF spokesman said in a statement. Dozens of concerned northern residents reported unusually high levels of Air Force activity over the Krayot, Nahariya and the Western Galilee during the afternoon. The IDF remains on high alert across the North, following Hizbullah threats to retaliate for February's assassination of its operations commander Imad Mughniyeh, in which Israel has denied any role. Late Friday night, IDF ground forces made up of Givati infantry soldiers, backed by Engineering Corps armored vehicles, withdrew from Gaza after raiding a series of targets close to the El-Bureij refugee camp, a military spokeswoman said Saturday evening. Palestinian sources said eight people were killed in the raids. The IDF said gunmen were hit during exchanges of fire. According to Gaza sources, the deaths bring the Palestinian casualty toll to 16 in IDF operations since Wednesday's terror attack on the Nahal Oz fuel depot, which killed two Israeli civilians. Prime Minister Ehud Olmert has pledged to keep hitting Hamas so that it cannot "continue to operate against Israeli civilians as it does." On Thursday night, two Hamas gunmen were killed by two IAF strikes near Khan Yunis, in the southern Gaza Strip, Palestinian officials reported. Seven other Palestinians were wounded in the attacks, they said.