Israel was engaged in "ongoing combat" on its northern border with Lebanon on Monday, the army said, as AFP correspondents on both sides of the frontier reported hearing loud explosions. There was no immediate official comment on the nature of the fighting, but a Lebanese TV station loyal to the Shiite group Hezbollah said Israel had been shelling targets across the border. "Ongoing combat in the Mount Dov area, northern Israel," Israeli army spokesman Jonathan Conricus said on Twitter, referring to a disputed area claimed by Lebanon that the United Nations considers part of the Israeli-occupied Golan Heights. Israel's army ordered all residents along the Blue Line that separates Israel and Lebanon to stay indoors. "Any kind of activity in open areas is forbidden," it said. Israel has in recent days placed its northern border on high alert and sent troop reinforcements to the area. The deployment followed widespread reports in Israeli media of a possible retaliation from Hezbollah after one of its fighters was killed in air strike in Syria that was blamed on Israel. Hezbollah has a substantial presence in Syria, where it is fighting in support of the Damascus government in the country's civil war. Israel hit Syrian army targets late Friday after munitions were fired across the Syrian border into Israel. burs/bs/fz