At least 14 people were killed and some 50 wounded Friday when a gunman opened fire at a crowded cinema premiere of the latest Batman movie in the US state of Colorado, police and media said.
Witnesses interviewed by local media described a scene of chaos at the midnight showing of "The Dark Knight Rises," saying the gunman had set off tear gas bombs and opened fire in the packed theater in Aurora, a suburb of Denver.
"Witnesses tell us he released some sort of canister," said Aurora police chief Dan Oates. "They heard a hissing sound and some gas emerged and the gunman opened fire."
Ten people were killed at the scene and another four died later at local hospitals, he said, adding that police had arrested the alleged gunman and that there was "no evidence" of a second, after earlier reports of two shooters.
Oates said the suspect had claimed to have explosives at his residence and that the apartment complex where he lived had been evacuated and was being searched.
Police spokesman Frank Fania told CNN the suspect was in his 20s, wearing body armor and armed with a rifle and two handguns, adding that he had set off some kind of smoke device in order to sow panic.
Witnesses described chaos chillingly similar to that depicted in the Batman films -- in which maniacal villains terrorize Gotham City -- suggesting the movie could have inspired the shooting spree.
They said several audience members had shown up in costumes, which could have allowed the gunman to blend in with the melee and complicated the arrest.
Police did not provide details about the killed and wounded, but the PG-13 film would have attracted scores of teenagers.
One witness cited by the Denver Post said he was watching the film when he heard a series of explosions. Bejamin Fernandez, 30, said people ran from the theater and there were gunshots as officers shouted "Get down!"
Another witness described how, during one of the action scenes, there was gunfire and what sounded like firecrackers, but people thought it was coming from the movie.
"So we just kept watching the movie for a little bit," the witness, identified only as Jack, told ABC television. Then it became clear that there was a real gunman in the theater.
"Everyone started panicking after that, because people were getting hurt," he said.
Aurora is barely 20 miles (32 km) from the scene of the 1999 Columbine High School massacre, in which two students shot dead 13 people and wounded 24 before committing suicide. The attackers had plotted the killings for a year.