Details of the Islamic State group’s recent ruthless torture tactics in Iraq have begun to surface as survivors told reporters and officers about the brutality they’ve witness while in hiding. Along with reports of babies taking bullets to the head and middle of the night executions, officials have also reportedly uncovered a massive gravesite with over 100 decapitated bodies, BBC reported.

A provincial council member in Nineveh told Reuters the town’s agricultural college was used as “a killing field” to slaughter hundreds of people under the Islamic State’s suspicion before Iraqi officials invaded the area.

Riyad Ahmed, whose father was killed by ISIS militia along with five other people he knew, also witnessed ISIS brutality and said Islamic State members would “torture them inside and then take them out of the neighbor and shoot them or slit their throats.”

Another man, identified only as Tariq, said he and several of his neighbors barricaded themselves in his house for four days, resisting ISIS demands to leave for the city of Mosul, where jihadists have retreated to. Tariq said he witnessed ISIS members trick families out of their homes by pretending to be Iraqi army officials, after which he said civilians would be executed on sight. The group took mercy on no one, including a one-year-old baby who Tariq said was killed with a “bullet in his head.”

Along with reports of babies being shot to death and middle of the night executions, officials have also reportedly uncovered a massive gravesite with over 100 decapitated bodies, BBC reported.

Although thousands were saved when the Iraqi army started arriving in the city of Hamam al-Alil as part of an U.S.-supported operation that started Oct. 17, hundreds were killed prior to the invasion. Many of the body parts Iraqi troops discovered at the gravesite about 19 miles south of Mosul had been reduced to skeletons, according to reports, so officials may not be able to identify all of them.

It was not immediately clear if the graveyard was filled with remains of civilians or police officials, but the site was being investigated to determine if the grave at Hamam al-Alil was also linked to the deaths of 50 former police officers who were killed at the same location in October, the Office of the UN High Commissioner for Human Rights said Tuesday.