A lone gunman dressed in riot gear burst into a movie theater in Aurora, Colo., at a midnight showing of the Batman film "The Dark Knight Rises" and methodically began shooting patrons, killing at least 12 people and injuring at least 50.

The suspect, James Holmes, 24, of Aurora, was caught by police in the parking lot of the Century 16 Movie Theaters, nine miles outside Denver, after police began receiving dozens of 911 calls at 12:39 a.m. MT. Police said the man appeared to have acted alone.

Witnesses in the movie theater said Holmes crashed into the auditorium through an emergency exit about 30 minutes into the film, set off a smoke bomb, and began shooting. Holmes stalked the aisles of the theater, shooting people at random, as panicked movie-watchers in the packed auditorium tried to escape, witnesses said.

"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.

Police said 10 victims died inside the theater, while dozens of others were taken to local hospitals, including a child as young as 6 years old.

A San Diego woman identifying herself as James Holmes's 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 may 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."

Holmes was wearing a bullet-proof vest and riot helmet and carrying a gas mask, rifle, and handgun, when he was apprehended, according to police. Holmes mentioned having explosives stored, leading police to evacuate his entire North Aurora apartment complex and search the buildings early this morning.

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.

"The suspect throws tear gas in the air, and as the tear gas appears he started shooting," said Lamar Lane, who was watching the midnight showing of the movie with his brother. "It was very hard to breathe. I told my brother to take cover. It took awhile. I started seeing flashes and screaming, I just saw blood and people yelling and a quick glimpse of the guy who had a gas mask on. I was pushed out. There was chaos, we started running."

One witness said she saw people dropping to the ground after the gunshots began.

"We were maybe 20 or 30 minutes into the movie and all you hear, first you smell smoke, everybody thought it was fireworks or something like that, and then you just see people dropping and the gunshots are constant," witness Christ Jones told ABC's Denver affiliate KMGH. "I heard at least 20 to 30 rounds within that minute or two."

A man who talked to a couple who was inside the theater told ABC News, "They got up and they started to run through the emergency exit, and that when she turned around, she said all she saw was the guy slowly making his way up the stairs and just firing at people, just picking random people," he said. "The gunshots continued to go on and on and then after we didn't hear anything...we finally got up and there was people bleeding, there was people obviously may have been actually dead or anything, and we just ran up out of there, there was chaos everywhere."

Witnesses and victims were taken to Gateway High School for questioning.

Hundreds of police and FBI agents are involved in the investigation. A senior official who is monitoring the situation in Washington said that early guidance based on the early snapshot of this man's background indicated that this act does not appear to be linked to radical terrorism or anything related to Islamic terrorism.

Though police have said that they believe the shooter was acting alone, they checked all cars in the parking lot and cleared the area near the theater.

In a statement, President Obama said, "Michelle and I are shocked and saddened by the horrific and tragic shooting in Colorado. Federal and local law enforcement are still responding, and my administration will do everything that we can to support the people of Aurora in this extraordinarily difficult time. We are committed to bringing whoever was responsible to justice, ensuring the safety of our people, and caring for those who have been wounded."

A man who was in the adjacent theater with his son, said that the commotion began as one of the action scenes was starting up.

"These guys came through, and they say someone's shooting," he said. "I thought, 'Oh, they must have heard the fireworks, you know ... I had no idea. And then the alarms started to go off in the theater.'"

An explosive device was also found inside the movie house. Police are not sure whether the device, which investigators are calling a bomb, was already in place or whether it was thrown into the crowd.

Ambulances rushed to the scene as audience members fled the theater.

Investigators are now interviewing friends and associates of the suspect to get a sense of the man's background.

The biggest problem is when these situations occur, people think about what they could have done about this or that after the fact. Tragedies like this happen because no one is paying attention or caring much about what's going on around them. I'm not trying to make light of this situation in the least, but instead waiting until after something happens, pay attention to the people around you. Often times people go out to do something like this, there is something different about them, whether it be small or large. The school shootings, what are the measures that can be taken to stop something like that from happening before it happens. Our own vigilance can help reduce things like this from happening, or at the least, keep casualties close to nothing.

That being said, this is ridiculous. And actually, there have been several shootings going on every year, just not a lot of them get as much press coverage. There was a school shooting only a few months ago. I don't remember what state, but it happened, got a few minutes of coverage and then it was out the window so we could hear more about the politics of our nation. The occurrences of things like this have been pretty frequent (more frequent than we realize anyway). Hopefully things can be done to help keep something like this from occurring again... but it most likely will.

I agree, but I think in a dark movie theater... well crap. He just busted in and started murdering, so I don't think these were people dealing with him day to day. Though, the fact that his mother said "He definitely did it" makes me mad, because if so- why hadn't she actually DONE something about the fact he was off? And now people are injured, dead, and other decent families suffering.

It's the part you said about the mother that I mean. The people we see and talk to most regularly are the ones we need to keep an eye on and see if behavior is off. People often don't pay attention or don't care, and the eventually leads to things like this in most cases.