TRIPOLI, Libya – Retreating loyalists of Moammar Gadhafi killed scores of detainees and arbitrarily shot civilians over the past week, as rebel forces extended their control over the Libyan capital, survivors and a human rights group said Sunday.

In one case, Gadhafi fighters opened fire and hurled grenades at more than 120 civilians huddling in a hangar used as a makeshift lockup near a military base, said Mabrouk Abdullah, 45, who escaped with a bullet wound in his side. Some 50 charred corpses were still scattered across the hangar Sunday.

New York-based Human Rights Watch said the evidence it has collected so far “strongly suggests that Gadhafi government forces went on a spate of arbitrary killing as Tripoli was falling.” The justice minister in the rebels’ interim government, Mohammed al-Alagi, said the allegations would be investigated and leaders of Gadhafi’s military units put on trial.

So far, there have been no specific allegations of atrocities carried out by rebel fighters, though human rights groups are continuing to investigate some unsolved cases.

Reporters with The Associated Press have witnessed several episodes of rebels mistreating detainees or sub-Saharan Africans suspected of being hired Gadhafi guns. Earlier last week, rebels and their supporters did not help eight wounded men, presumably Gadhafi fighters, who were stranded in a bombed out fire station in Tripoli’s Abu Salim neighborhood.