TWELVE people, including a number of children, have been shot dead at a midnight screening of the Batman film The Dark Knight Rises, at a shopping mall cinema in a Colorado city.
Another 60 people were injured in the shooting, believed to have been carried out by a lone gunman just after midnight as the film was about to begin at the packed cinema.
There were reports that a 1-year-old child was shot at point-blank range as the gunman made his way through the cinema with a shotgun and a handgun, picking out his victims at random after setting off a tear gas canister.
Ten people were known to have been killed in the shooting inside the theatre.
A police spokesman confirmed another four died on the way to hospital.
Police confirmed one suspect was in custody.
He was detained near a car behind the Century Aurora 16 in the town of around 325,000 people.
He was found to be carrying a gas mask, rifle and handgun.
Police had also been searching for an explosive device outside the cinema.
They had been searching for a second suspect but said at a press conference there was currently "no evidence" of a second gunman.
They remained "concerned" and were trying to obtain more information.
Fox News reported that police were searching the suspect's apartment in Aurora.
Brenda Stuart, of 850 KOA Radio said the victims were shot dead but there may have also been an explosion.
Stuart told Sky News: "This started with a midnight showing of the new Dark Knight movie and the theatres were packed that were showing this movie.
"People inside tell us they thought it was part of the movie. They heard what they thought were firecrackers, loud bangs and all of a sudden they saw the bullets flying.
"Police officers are carting the injured to the hospital in their own cars, not waiting for the ambulances."
A makeshift hospital was set up at the mall to treat those wounded in the attack.
A witness told 9News that during a shooting scene in the film he heard loud bangs and a lot of smoke and initially thought they were live special effects put on by the cinema.
Projectiles came through the wall from the neighbouring theatre screening, where it appears the shooting occurred.
Witness Justin Joseph told local media that as the film was about to start a moviegoer stood up and turned to face the audience wearing a gas mask and body armour.
Witnesses heard two loud bangs which turned out to be tear gas. As mass panic broke out, people started to run and the gunman opened fire on "moving targets".
Another CNN quoted another witness as saying he saw a "guy slowly making his way up the stairs and firing, picking random people".
The BBC quoted the FBI as saying they were working with the local police but said it was still too early to say if there was a terrorism link.
Police Chief Dan Oates said city police were checking the area for explosives.
Police believed more weapons may have been left in the cinema and the arrested man told them explosives were stored at his home.
He appealed to the public for information.
"The scene is still very active and we have little information for release at this time," police spokeswoman Cassidee Carlson said in a brief news release.
The suspect also indicated that there may be explosives in a Hyundai parked in the car park at the cinema.
Another witness reported seeing a police officer carrying an injured girl out of the building with gunshot wounds to her back.
Frank Fania of Aurora police told CNN the suspect was a younger adult male.
He could not give an exact age but he believed he was in his early 20s.
Hundreds of witnesses were taken by bus to a nearby high school for questioning.
Denver and Aurora are the principal cities of the Denver metropolitan area.
Another witness said the attacker was dressed all in black and was wearing a riot helmet, bulletproof vest and goggles.
Cellphone footage taken by a movie-goer inside the cinema showed scenes of chaos as people tried to flee the building.
Sky News broadcasting the cellphone footage showing bloodied moviegoers staggering through the foyer as panic ensued.
One man shown with blood seeping from his shoulder being escorted out by a police officer.
Some filmgoers were shown wearing Batman outfits, suggesting a man in a mask and body armour would not have looked out of place.
It was understood some off-duty police officers were in the cinema and were involved in the arrest.