Amnesty International on Wednesday urged for the release of at least six protesters abducted when armed men, apparently allied with Libya’s U.N.-supported government, fired live ammunition to disperse a demonstration in the capital.

The incident took place on Sunday when protesters rallied in Tripoli and elsewhere in western Libya against deteriorating economic conditions and corruption.

Amnesty said armed men in military uniform opened fire on the crowd without warning, using AK-style rifles and truck-mounted guns.

The Interior Ministry accused “outlawed infiltrators” of firing at the protesters on Sunday and said an investigation was opened.

The London-based group said that along with the six abducted, several protesters were wounded in the shooting, which happened in an area that’s under control of the Nawasi militia that nominally operates under the U.N.-supported government in Tripoli.