A gunman wearing a gas mask has killed 14 people when he opened fire at a Colorado cinema on the opening night of the latest Batman movie. At least 50 others were injured.
The gunman was aged in his early twenties, Aurora police spokesman Frank Fania said. FBI spokesman Jason Pack said there was no indication so far of any connection to terrorism.
President Barack Obama said he was "shocked and saddened" by the "horrific and tragic" shooting. It was apparently the worst mass shooting in the US since the 2007 shooting on the Virginia Tech campus.
The gunman stood at the front of the cinema and fired into the crowd. He was later taken into custody near a car behind the cinema.
"Witnesses tell us he released some sort of canister. They heard a hissing sound, and some gas emerged and the gunman opened fire," Aurora Police Chief Dan Oates told a news conference. Mr Fania told ABC that investigators do not believe anyone else was involved.
Emergency crews rushed to the scene after frantic calls started flooding the switchboard. Officers ran in and told people to leave the cinema, Salina Jordan told the Denver Post newspaper. She said some police were carrying and dragging bodies.
"A gas mask, rifle, handgun at least one additional weapon (were) found," Mr Oates said. The suspect's name was not released. There was 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
Police were at the Denver-area apartment and had evacuated other residents of the building. Mr Oates did not say whether explosives had been found. He said police also checked for explosives at the Century 16 theatre and secured those areas. The police chief said 10 victims died at the cinema and four at area hospitals. At least 24 people were being treated at hospitals.
Movie-goers spoke of their terror as violence erupted and people around them were shot. Benjamin Fernandez, 30, told the Post he heard a series of explosions. He said people ran from the theatre and there were gunshots as police shouted "Get down!"
Ms Jordan told the paper that one girl was struck in the cheek, and others were struck in the stomach, including a girl who looked to be around nine years old.