A car exploded near a police station in Libya's eastern city of Benghazi late Tuesday, a police officer told AFP, adding that two of his colleagues were injured in subsequent clashes.
The attack came as the country's new authorities try to empower the national army and police but struggle to rein in armed militias born out of the 2011 conflict that toppled long-time dictator Moamer Kadhafi.
The vehicle belonged to a police officer who was posted in the area of Ras Obeida, the same source said on condition of anonymity.
There were no casualties or major material damage from the blast, which was believed to have been sparked by a hand grenade or fishing explosives.
But two policemen were later injured in a gunfight with the key suspect.
"One of them is in a critical condition and the other was hit on his foot," said the police officer, adding that the suspect had escaped.
The explosion ripped off the nose of the vehicle which had been parked outside the officer's home, just behind the Ras Obeida police station, an AFP journalist said.
The Mediterranean city of Benghazi, cradle of the 2011 uprising against Kadhafi, has endured several blasts, while a September 11 attack by militants on the US mission in Benghazi killed four Americans, including ambassador Chris Stevens.
The city has also witnessed a wave of assassinations, targeting officials with links to the former regime, which are often blamed on hardline Islamists.
On Tuesday, also in Benghazi, the bullet ridden corpse of retired colonel Abdelkarim Mahfud, who backed the 2011 revolution, was found in his farm.
Libya successfully held its first elections in July, following 42 years of dictatorship, but the new authorities are hard pressed to provide security in the face of widespread arms and a weak security apparatus.