BEIRUT (AP) — Missiles fired by Syrian warplanes hit Lebanese territory today in one of the most serious crossborder violations since Syria’s crisis began 18 months ago, security officials in Beirut and Lebanese state media said.

The officials, speaking on condition of anonymity in line with regulations, said four missiles fired by two Syrian jets hit a rugged and remote area on the edge of the Lebanese border town of Arsal. There were no immediate reports of casualties.

Lebanon’s state-run National News Agency reported that the warplanes fired three missiles that fell on the outskirts of Arsal about 500 yards from the border between the two countries.

“I heard several explosions and saw four clouds of dust billowing from the area,” Arsal resident Nayeh Izzedine said by telephone referring to the border. “I don’t know if it was an air raid but there was a plane in the sky.”