A gunman killed at least 14 people and injured 50 others early Friday at a suburban Denver, Colorado, movie theater, authorities said.

Aurora Police Chief Dan Oates said 10 people were killed when gunfire erupted at a theater showing the latest Batman movie "The Dark Knight Rises," and four others died at area hospitals.

Oates said that a 24-year-old suspect was in custody and there was no evidence of a second shooter.

A gas mask, a rifle and handguns were found in the suspect's vehicle. An apartment building in north Aurora connected to the suspect was being evacuated and searched for possible explosives.

Witnesses said the masked man wearing a bullet-proof vest opened fire and set off a smoke bomb at the Century 16 Movie Theater in Aurora Mall, located on the southeast outskirts of Denver.

"Witnesses tell us he released some sort of canister. They heard a hissing sound and some gas emerged and the gunman opened fire," Oates said at a news conference.

Police and firefighters rushed to the mall shortly after the shootings occurred around 12:30 am local time (0630 GMT).

CNN reported at least 20 people were being treated for gunshot wounds in hospital, three of them in serious condition.