Bombs flattened a police station in the eastern Libyan city of Benghazi on Wednesday but there were no casualties as the building had been emptied for repairs following previous attacks, security officials said.
The al-Hadaiq station in downtown Benghazi was completely destroyed by explosives at around 0300 a.m. (0100 GMT). The blast was so loud it could be heard across the city.
Smashed furniture littered the ground and nearby shopfronts were damaged.
"From the debris, it looks as if explosive devices were placed all around the building," said Mohammed al-Hajazi, spokesman for Benghazi's operation room.
Last month the station was set on fire in a possible act of revenge for the killing of a man in an attack on police nearby.
Libya remains anarchic and awash with weapons nearly two years after dictator Muammar Gaddafi was toppled.
Tensions have been rising between militia groups of former rebel fighters and the government, which is still struggling to assert its authority.
Benghazi, the cradle of the 2011 uprising against Gaddafi, has became a hot spot for violence, with a wave of attacks on security forces.
On Saturday, six soldiers were killed and five injured in clashes between Libyan special forces and armed protesters outside a special forces base in Benghazi.