A gunman wearing a gas mask set off an unknown gas and fired into a crowded movie theater in suburban Denver at a midnight opening of the Batman movie “The Dark Knight Rises,” killing 12 people and injuring at least 50 others.

According to the Moviegoers many didn’t know what was happening and some thought the attack was part of the show. Then they saw a silhouette of a person in the smoke at the front of the theater near the screen, pointing a gun at the crowd.

Some of those injured are children, including a 3-month-old infant.

Police earlier said 14 people were dead, but later revised the number to at least 12.

The shooter, a man in his 20s, was arrested shortly after the attack at 12:30 a.m. at the multiplex theater at a mall in Aurora. The suspect was taken into custody has been reportedly identified as 24-year-old James Holmes of North Aurora.

A gas mask, rifle, handgun and at least one additional weapon (were) found inside the theater. Investigators are now in the process of searching Holmes’ apartment which has been evacuated due to fears of explosive devices.

At least 24 people were being treated at Denver area hospitals at last count.