A Connecticut shop that sold a gun to the Newtown school shooter's mother has lost its federal firearms license.

The Bureau of Alcohol, Tobacco, Firearms and Explosives revoked the license of Riverview Gun Sales in East Windsor, about 15 miles north of Hartford, in December. The agency didn't disclose why. It was first reported Thursday by The Journal News of White Plains, N.Y.

Authorities raided the store for undisclosed reasons shortly after the December school shootings. Around the same time, a man was arrested for stealing a rifle from the shop.

Shop owner David LaGuercia has said Nancy Lanza bought a gun from him years ago, but couldn't remember what kind.

Adam Lanza killed 20 first-graders and six adults with his mother's rifle. He also killed his mother and himself.