At least 14 people were killed and over 50 others injured after a masked gunman in a gas mask and body armor opened fire at a packed midnight showing of the new "Batman" film in a Denver suburb on Friday.
Witnesses at the movie theater told of a horrific scene, with dazed victims bleeding from bullet wounds, spitting up blood and crying for help.
Among those taken to hospitals as a precaution was a 3-month-old baby boy.
"I slipped on some blood and landed on a lady. I shook her and said, 'We need to go, get up,' and there was no response, so I presumed she was dead," said Tanner Coon, 17.
"I went toward the exit, waited in the exit for my friends and saw a guy with blood across his face and shoulders, and just got out of the movie theater."
According to reports, the heavily armed suspect, who was wearing a bulletproof vest, has been taken into custody. He hurled a gas canister into the crowded multiplex theater.
Suspect was arrested in parking lot behind the theatre.
The suspect's apartment building has been evacuated. The suspect is believed to be in his early 20s.
According to an eye witness, he was carrying a knife, a rifle, a handgun when arrested and one other gun was recovered from the theatre.
The gunman "appeared at the front of the screen" in the theatre and started shooting. Police added that the suspect said that he had explosives in his aprtment and that this claim was being investigated.
Three patrons have been seriously injured in the shootout during the screening.
Police, who initially said 59 people were hurt, said 30 people remained hospitalized on Friday evening, 11 of them in critical condition.
It said local hospitals were alerted to a "mass casualty incident".