Tripoli, Libya (CNN) -- Eyewitnesses say Gadhafi loyalists killed "numerous detainees" this week at two military camps in Tripoli, Amnesty International reported on Friday.
Escaped detainees from the Khilit al-Ferjan and Qasr Ben Ghashir camps provided testimony to the human rights group.
The loyalist forces used grenades and gunfire on scores of prisoners at Khalit al-Ferjan after around 160 detainees fled a metal hangar.
"I was in shock when the grenades exploded," escaped detainee Akram Mohamed Saleh said.
"There was so much confusion around me, smoke all around, people screaming for help and trying to flee. I saw dozens of bodies, and I was covered with blood and human flesh."
Guards loyal to Gadhafi at Qasr Ben Ghashir shot and killed five detainees captured during the conflict and held in solitary cells.
Amnesty said Gadhafi's "troops continue their flagrant disregard for human life and international humanitarian law. It is a war crime for any party to a conflict to kill or torture prisoners."
"Loyalist forces in Libya must immediately stop such killings of captives, and both sides must commit to ensuring no harm comes to prisoners in their custody," the group said, noting that the killing prisoners in a conflict is a war crimes.