Eighteen prisoners have escaped during an attack on a Libyan police vehicle taking them back to prison from a courthouse in the capital, a police spokesman said on Friday.
Thursday's attack is the latest in a string of incidents plaguing Libya and comes after more than 1,200 inmates escaped during a prison riot last week in the restive eastern city of Benghazi.
Judicial police spokesman Ahmad Boukraa said the prisoners were being transported back to Ain Zara prison in a western suburb of Tripoli when gunmen attacked the police vehicle, seriously wounding two guards, Lana news agency reported.
Boukraa gave no further details.
Libya's authorities have been struggling to reestablish law and order and form a professional police and army since the fall of longtime dictator Moamer Kadhafi in 2011.
On July 27, more than 1,200 inmates escaped from Al-Kuifiya prison in Benghazi, with a security official saying most of them were common law detainees.
He said they broke out during a riot "as well as an attack from outside."
In April armed men attacked a convoy of prisoners near Tripoli, killing a detainee and wounding others.