As many as 15 people were killed and 23 others were wounded when a school which had been rigged with explosives to the west of Mosul, Turkey's Anadolu Agency reported a military source saying.
"Fifteen people were killed, including 12 from the Tribal Crowd forces and 23 others were injured when a booby trap exploded in a school in the village of Majarin between the town of Badush and Tal Afar, 60 kilometres west of Mosul," Captain Durgam Haidar Al-Mawla told the news agency.
"The Tribal Crowd used the school for training after receiving the task of protecting the village along with the 73rd Brigade in the Iraqi army."
Al-Mawla explained that some of the victims were in the houses surrounding the school," adding that some of the school rooms were booby-trapped with improvised explosive devices.
The Tribal Crowd are pro-government Sunni forces which were formed in 2014 after Daesh controlled many Iraqi cities and provinces.
No one has claimed responsibility for the explosion.