Six soldiers were killed in clashes between Libyan special forces and armed protesters outside a special forces' base in the eastern city of Benghazi, an military official said on Saturday.
Residents in the area said heavy gunfire and explosions were heard during the fighting and hours earlier a group of men had forced their way into a different army compound to steal weapons.
"The clashes lasted from 2:00 a.m. (0000 GMT) until 6:00 a.m. but are over now," Colonel Mohammed Sharif, of the special forces in Benghazi, told Reuters.
It was not immediately clear who the protesters were and if any had been killed.
Last week at least 31 people were killed and 100 injured in clashes between armed protesters, eventually backed by special forces, and a militia in the city.
The protesters had been demanding the disbanding of militias, and clashed with members of the Libya Shield brigade, which fought to oust former leader Muammar Gaddafi and now says it is aligned with the defence ministry.