Police now say the Colorado movie theater shooting suspect's apartment is booby- trapped and the area is being evacuated.  Twelve people are dead and at least 38 are injured following a shooting at a movie theater in Aurora, Colo. Police say the gunman opened fire in a theater during a midnight premiere showing of the latest Batman movie, "The Dark Knight Rises." One of the injured was just 3 months old.

Authorities have identified the suspect as 24-year-old James Holmes, who reportedly submitted to police quietly. He's in police custody. The FBI says there's no indication that the shooting is linked to any terrorist groups.

Holmes reportedly entered the theater in a rear door, put on a gas mask and a bullet-proof vest, threw tear gas into the crowd and started shooting. Police found four guns, including an assault rifle resembling an AK-47.

Police say people inside the movie first heard a hissing sound and then gas emerged. Hayden Miller tells KUSA-TV that he heard several shots that sounded like "little explosions going on and shortly after that we heard people screaming." Miller says at first he thought the sounds were from a louder movie next door, then he saw "people hunched over" leaving the theater.

"There were so many people running," Adam Witt told CNN. "I didn't look back. I just remember getting up from the floor and shouting, 'We have to run.'"

It's the worst mass shooting in Colorado since the Columbine High School attack in 1999.

President Barack Obama issued a statement on the shooting, saying he and his wife, Michelle, were "shocked and saddened."

"As we do when confronted by moments of darkness and challenge, we must now come together as one American family," Obama said.

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ABC News spoke briefly with Holmes' mother. Here's video: