A gate blown apart at a police station in the city of Benghazi.
This was one of two stations targeted by bombers in the city which was the birthplace of the uprising that toppled Muammar Gaddafi in 2011.
There were no casualties but the blasts damaged buildings, including a nearby school.
A second blast shattered windows at this station.
(SOUNDBITE) (Arabic) GUARD AT POLICE STATION ABDULLAH AL-ZAYID, SAYING:
"Just after my dawn shift ended and at the time we were leaving the police station, somebody put something outside and it exploded, smashing glass and damaging the building and the cars around."
Meanwhile, hundreds gathered in the city to call for a Libya free of weapons.
Libya has been plagued by violence in recent months as the central government has struggled to subdue heavily-armed local militias.
Britain temporarily cut staff at its embassy in the capital Tripoli because of security fears.