SUTHERLAND SPRINGS, Texas - CBS News has confirmed that a mistake by the U.S. Air Force may have allowed the gunman, 26-year-old Devin Patrick Kelley, to buy his weapons.

He bought at least two guns after passing background checks, despite receiving a bad conduct discharge from the U.S. Air Force. That discharge should have prevented him from making firearm purchases.  

The Air Force admitted Monday that its Office of Special Investigations apparently failed to report Kelley's name to the National Criminal Information Center after he pleaded guilty to two counts of domestic violence in 2013.

Because his name did not appear in the database, Kelley was able to walk into a gun shop in San Antonio last year and buy the semiautomatic rifle police have identified as the weapon used to kill 26 people.

Authorities believe Kelley, died of a self-inflicted gunshot wound, the sheriff in Sutherland Springs told CBS News.

Wilson County Sheriff Joe Tackitt told CBS News correspondent Jeff Glor that Kelley shot himself after he tried to get away from the First Baptist Church in Sutherland Springs.

Kelley was being chased by two men in a truck after attacking the church during Sunday morning services.