The apartment of the suspect in the Colorado mass shootings is booby-trapped police said today.
The building had been evacuated earlier after the alleged shooter, 24-year-old James Holmes, told police of “possible explosives in his residence.”
Authorities evacuated five buildings as they determined how to disarm flammable and explosive material.
The development came as the name of Aurora, Colorado, was today added to the long list of American communities devastated by a shooting spree killing.
Police confirmed that 12 people had been shot dead by a gunman who fired into a crowded Colorado cinema audience during a midnight showing of the latest Batman film 'The Dark Knight Rises'.
The gunman, who is now in custody, is also thought to have released an as yet unidentified gas into the crowd of cinema-goers.
He has been named as 24-year-old James Holmes.
At least 50 people are reported to have been injured in the shooting - the largest mass shooting in the US since the 2007 Virginia Tech campus attack.
The gunman reportedly began firing during a shoot-out sequence, confusing some of the crowd who thought the shooting was part of the show.
Witnesses say they saw a silhouette of the shooter in the smoke at the front of the theatre, pointing a gun at the crowd.
“I told my friend, 'We've got to get out of here,' but then he shot people trying to go out the exits,” Jennifer Seeger told NBC's “Today.”
The youngest injured victim was a 3-month-old baby, and there were reportedly a number of children in the crowd.
Witnesses say after releasing the gas into the auditorium the gunman walked up the cinema aisle - shooting indiscriminately.
James Holmes was arrested in a car park near the cinema shortly after the incident at the multiplex theatre in Aurora.
President Obama today described the shooting as “horrific and tragic”, and said he was saddened by the incident.
The Paris premiere of 'The Dark Night Rises', which was planned for tonight - has been cancelled following the shooting.
Workers were seen taking up the red carpet and removing a large mask from the front of the theatre.
The FBI, who are working in conjunction with police at the scene, said there was no evidence that the attack was related to terrorism.
There is currently no word on motive, and contrary to earlier reports police say there is no evidence of a second gunman.
Aurora Police Chief Dan Oates said: “A gas mask, rifle, handgun at least one additional weapon (were) found,” Oates said.
Police also evacuated the area around the cinema to search for possible explosive devices.
It is currently not clear whether or not any explosives were found, though police later confirmed that Holmes' apartment had been 'booby-trapped'.
The latest in the series of Batman films is currently the subject of much political debate, following claims from right-wing radio host, Rush Limbaugh, that the film's villain 'Bane' is a reference to Mitt Romney, the Republican presidential contender. Romney is the founder of Bain Capital a finance company.
Moviegoers today described their horror as the events unfolded.
Benjamin Fernandez, 30, said he heard a series of explosions.
He said people ran from the theatre and there were gunshots as police shouted “Get down!”
KUSA-TV reported that some victims were treated for chemical exposure, related apparently to canisters thrown by the gunman.
Aurora is home to a large Defense Department satellite intelligence operation at Buckley Air Force Base.