"A gas mask, rifle, handgun at least one additional weapon (were) found inside" he said. The suspect was taken into custody, but no name was released. Mr Oates said there was no evidence of any other attackers. There was also no immediate word of any motive.
The suspect spoke of "possible explosives in his residence. We are dealing with that potential threat," Mr Oates said, without providing details on where that was.
He said police also checked for explosives in the car park and theatre, and secured those areas.
Witness Hayden Miller told KUSA-TV that he was inside Theatre 16 and heard several shots. "Like little explosions going on and shortly after that we heard people screaming," he told the station. Mr Hayden said at first he thought it was part of a louder film next door. But then he saw "people hunched over leaving theatre."
Local radio reporter Brenda Stuart said movie-goers thought the attack was part of the film at first. She told Sky News: "A lot of people thought the gunshots were part of the movie. "Then bullets started flying."