"You just smelled smoke and you just kept hearing it, you just heard bam bam bam, non-stop. The gunman never had to reload. Shots just kept going, kept going, kept going," one witness told ABC News.
"I'm with coworkers and we're on the floor praying to God we don't get shot, and the gunshots continue on and on, and when the sound finally stopped, we started to get up and people were just bleeding," another theatergoer said.
The suspected shooter will face his first court appearance next week, according to district attorney Carol Chambers.
Holmes, originally of San Diego, moved to Aurora to pursue his Ph.D. at the University of Colorado medical center, living blocks from the hospital in an apartment that police say is now laced with explosives and being searched by HazMat teams.
Federal law enforcement sources told ABC News that Holmes bought a ticket to the movie, slipped out of the theater once it began and propped open the emergency exit before gathering his weapons and gear and coming back into the theater. Once inside, he opened fire.
A San Diego woman identifying herself as James Holmes' mother spoke briefly with ABC News this morning.
She had awoken unaware of the news of the shooting and had not been contacted by authorities. She immediately expressed concern that her son might have been involved.
"You have the right person," she said.
"I need to call the police," she added. "I need to fly out to Colorado."
The woman and her husband later released a statement saying their "hearts go out to those who involved in this tragedy and to the families and friends of those involved. We are still trying to process this information and we appreciate that people will respect our privacy."
The highly anticipated third installment of the Batman trilogy opened to packed auditoriums across the country at midnight showings this morning, and features a villain named Bane who wears a bulletproof vest and gas mask. Trailers for the movie show explosions at public events, including a football game. Though many moviegoers dressed in costume to attend the opening-night screening, police have made no statements about any connection between the gunman's motives and the movie.
Police in New York have intensified security around showings of the film throughout the five boroughs today, with Police Commissioner Ray Kelley saying that "as a precaution against copycats and to raise the comfort levels among movie patrons in the wake of the horrendous shooting in Colorado, the New York City Police Department is providing coverage at theaters where the 'The Dark Knight Rises' is playing."
The Paris premiere of the movie has been cancelled in the wake of the shootings. "Warner Bros. and the filmmakers are deeply saddened to learn about this shocking incident. We extend our sincere sympathies to the families and loved ones of the victims at this tragic time," the movie's producers said in a statement.
Witnesses watching movies in theaters next to the one where the shooting took place said bullets tore through the theater walls and they heard screaming.