Human Rights Watch said Monday that the explosion struck the women's section of a Shiite mosque in the town of Daquq and appeared to have been caused by an airstrike, AP reported.
Residents believe it was an airstrike because of the extent of the destruction and because planes were heard flying overhead. It happened on Friday amid a large Daesh assault on the nearby city of Kirkuk.
The US-led coalition and the Iraqi air force are the only parties known to be flying aircraft over the country.