Ambulance helicopter shot down in Tripoli, 23 aboard

A helicopter with 23 people on board crashed Tuesday near the Libyan capital but the cause was unclear, a security official said. "We will respond strongly at the right time and place", Sharkasi said in a statement, referring to the Washafana fighters.

It called on citizens to "provide any information that can help to identify those who fired on the aircraft".

"When we first went by boat to retrieve the bodies, we were attacked from the coast near the Almaya area", he said, adding that Tripoli-allied groups then stopped the fire.

However, the helicopter ran into trouble on return back to Tripoli and was carrying a number of local residents, Reuters reports.

The capital was overrun in August 2014 by the Fajr Libya militia alliance which included Islamists.

The North African nation has seen widespread violence since the 2011 overthrow and killing of longtime leader Moamer Kadhafi.

The two governments are vying for power, and armed groups are battling for control of its vast energy resources.

Western Tripoli has been seeing clashes between Libya's Dawn militias and forces loyal to the internationally recognised House of Representatives (parliament). In the chaos, Islamic State militants have gained ground and people smugglers are taking advantage to ship illegal migrants to Europe.