PHNOM PENH, Cambodia (AP) — Villagers in northwestern Cambodia unearthed what could be a mass grave from the Khmer Rouge era with about 20 skulls and some leg bones bound with rope, officials said Monday.

The village is near a former Khmer Rouge prison and the site is believed to be one of the “killing fields” from the regime’s brutal rule in the 1970s. It wasn’t yet known if Saturday’s discovery of skulls and other skeletal remains involved more than 20 victims.