Rival groups loyal to the National Transitional Council in Libya have clashed outside the capital Tripoli.
Although officials insist the trouble has been under control, the BBC reports a number of people have been killed.
There have been fears that fighters who helped topple Muammar Gaddafi may turn on each other.
NTC chairman Mustafa Abdul Jalil blamed "irresponsible" elements among the former rebels for the outbreak.
Exchanges of gunfire continued for several hours on Saturday afternoon at Imaya on the main highway from the capital to the Tunisian border.