Two army troops were killed and three others wounded in a raid to arrest a fugitive in the Hermel area of Ras al-Assi on Sunday.
The fugitive, identified as Kh.A.D., was also killed in the operation.
TV networks added that there was a chase and that an army force was encircling the region.
An army statement said the troops were pursuing a stolen vehicle when the gunfight erupted.
The army patrol giving chase “was ambushed and came under fire,” the statement said.
It said one gunman was killed and the driver of the vehicle was arrested, without providing additional details.
Prime Minister Hassan Diab condemned the ambush, saying an attack on the army is an attack on all Lebanese.
“What is required at this moment is to speed up the arrest of the attackers,” he said, without identifying those responsible, in a statement carried by state-run National News Agency.