Twelve people were killed and at least 50 others wounded early Friday when a gunman opened fire 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 and two others died after being taken to local hospitals. A three-month-old and a six-year-old girl were among those treated, according to reports.

Police said the gunman had appeared at the front of the theater during the movie and released a canister which let out a hissing sound, which is believed to be tear gas. Witnesses told reporters that gunfire erupted during a shootout scene in the film.

A suspect was apprehended in the shopping center's parking lot, Oates said. He was named as 24-year-old James Holmes, two federal officials from different agencies told NBC News.

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.