Americans are mourning after 12 people were killed and 58 injured in an overnight shooting rampage at the premiere of a new Batman film in Aurora, Colorado.
The incident is one of the deadliest mass shootings in recent U.S. history.
The suspected shooter was identified as 24-year-old James Holmes.
Aurora, Colorado Police Chief Dan Oates said that 30 of the injured remained hospitalized, 11 in critical condition.
Holmes had entered the theater during the midnight premier of the new Batman movie, "The Dark Knight Rises."
Dressed in black, wearing a gas mask, and covered in body armor from head to toe, the suspect detonated two canisters of gas before opening fire on the packed auditorium.
Forensic evidence suggests that Holmes used an assault rifle, a shotgun, and a Glock handgun in the attack.
Oates told a news conference that Holmes had acquired thousands of rounds of ammunition for his arsenal.
"He purchased four guns at local metro gun shops and through the Internet he purchased over 6,000 rounds of ammunition -- more than 3,000 rounds of .223 ammunition for the assault rifle, 3,000 of .40 caliber ammunition for the two Glocks in his possession and 300 rounds for the 12-gauge shotgun," Oates said.
Holmes surrendered to officers who rushed to the scene.
Survivor Stephen Parton, who was lightly injured in the attack, described the attack.
"People started screaming, there was a lot of chaos. So I ducked down with my friends who I was there with and we were there... I don't know, he [Holmes] probably fired off about 25 rounds, I don't know, it is tough to remember," Parton said.
"And when it finally stopped, I got up and there were a lot of people rushing for the back left exit and I just joined them."
Bomb specialists have been trying to disarm explosive devices rigged as booby-traps left in Holmes's apartment. Police said a trip wire has been severed and one explosive device disarmed.
Nearby buildings have been evacuated and Oates said clearing the apartment could take several days.
The Federal Bureau of Investigations (FBI) said there is no apparent link between Holmes, a former graduate student in neuroscience, and any terrorist organization.
The Pentagon said at least three U.S. military members were among those wounded. A statement said a sailor and two airmen suffered injuries in the assault, and another U.S. Navy sailor remained "unaccounted for."
The Pentagon also said that Holmes has never served in any branch of the U.S. military.
U.S. President Barack Obama, speaking at a campaign event, said he was "shocked and saddened" by the "senseless" killing: "We will take every step possible to ensure the safety of all of our people. We're going to stand by our neighbors in Colorado during this extraordinarily difficult time."
He ordered U.S. flags lowered to half-staff for five days in honor of the victims.
Obama and his Republican rival Mitt Romney also canceled campaign speeches replacing them with expressions of sorrow for the victims.
The film's director, Christopher Nolan, issued a statement on behalf of the cast and crew, expressing their "profound sorrow at the senseless tragedy."
The shooting has prompted officials to cancel the Paris premiere of the film.
Based on reporting by AFP, AP, and Reuters