By David Wyllie, Ian Johnston and Dan Strieff, NBC News
Updated at 5:35 a.m. ET: At least 14 people were killed and dozens of others wounded early Friday when at least one gunman opened fire during a shootout scene at a midnight screening of the summer blockbuster "The Dark Knight Rises" near Denver, authorities and witnesses said.
Aurora police chief Dan Oates told reporters that 10 people died at the scene of the shooting and four others died after being taken to local hospitals. At least 50 other people were injured, Oates said.
One suspect was in custody, police said. It was unclear whether other suspects were involved.
The incident occurred in the Century 16 Movie Theaters at the Aurora Town Center, police told NBC News. Aurora is a suburb less than 10 miles east of downtown Denver.
Brenda Stuart, of 850 KOA radio, told Sky News that "a lot of people thought the gunshots were part of the movie."
"They heard what they thought were firecrackers," she added, citing witnesses. "Then they saw the bullets flying."
Eyewitness reports said the assailant may have been wearing a gas mask, Stuart said.
Tear gas went off in the theater following the gunfire, Stuart said. She added that bullets had passed from one theater into an adjoining one.
The Denver Post quoted witness, Bejamin Fernandez, 30, as saying that people ran from the theater as shots rang out and police shouted "get down!"
Fernandez told the Post that he saw people falling, including one young girl.
Salina Jordan, 19, who was in Theater 8, told the Post she saw one girl struck in the cheek and others in the stomach, including a girl who looked to be around 9 years old.
Jordan told the Post that someone ran into her theater yelling, "they're shooting out here!" An alarm came on, Jordan said, announcing there was a "murder in [the] theater."
Jordan told the newspaper she saw police carrying bodies out of the theater as well as officers opening fire.
KUSA cited a witness as seeing a black-clad 6-foot-tall man wearing a riot helmet, goggles and bullet-proof vest kick through the door. The witness and her boyfriend crawled to the emergency exit, KUSA said.
Police spokeswoman Cassidee Carlson said "the scene is still very active."
More on this story from breakingnews.com
Local emergency crews from several cities, including Denver and Boulder, have converged on the scene, Stuart told Sky News.
Cathy Canzanora, a 911 dispatcher, told NBC News that emergency dispatchers were deluged with calls from "everybody who had cellphones in the theater" at 12:39 a.m. Friday local time (2:39 a.m. ET).
"The place blew up," she said, referring to the number of calls.
She said she could not reveal what people told her but said that they reported "that there had been a shooting so we got the police and the fire department and the ambulance there as soon as they could."
Further local coverage from NBC station KUSA-Denver
Police cars transport the wounded
The injured were being transported to three local hospitals, police told NBC.
Nicole Williams, with the Swedish Medical Center of Englewood, Colo., told KUSA-Denver the hospital was alerted to a mass-casualty incident at 1:15 a.m. local time Friday (3:15 a.m. ET).
Emergency services attend the scene of a mass shooting at a movie theater in Aurora, Colo., early Friday.
Kalena Wilkinson, a public information officer for Denver Health, said six patients were taken to that hospital, with one in a critical condition and the other five in " fair" conditions.
KOA's Stuart said that police officers were taking victims to hospitals in their cars and not waiting for ambulances.
A bomb squad was on site, police added.
"The Dark Knight Rises," starring Christian Bale and Anne Hathaway, is the latest in the popular Batman action movie franchise. Friday was its international premier.