Shooting massacre at Colorado Batman premiere

At least 12 confirmed dead, 50 injured in worst shooting in U.S. since 2007 Virginia Tech. shooting

AURORA, CO (WACH / FOX NEWS / AP) -- Police are now saying12 people are confirmed dead and 59 people are wounded after a mass shooting that took place just after midnight Friday morning in Aurora, CO, according to Fox News. The shooting happened about a half hour into the midnight premiere of "The Dark Knight Rises" when a gunman set off an unknown gas and began firing shots into the crowd.

Police are confident the shooter acted alone, according to Fox News.

Federal law enforcement officials have identified the shooter as 24-year-old James Holmes. Holmes was wearing body armor and a gas mask while in the sold-out theater room at Century 16 Theater as previews began, according to Fox News. As the movie started, he began throwing what appeared to be tear gas or a smoke bomb and firing shots as the crowd of moviegoers erupted into chaos, according to Fox News. Police say he had two handguns and a long gun that he may have hid in the theater ahead of time, according to Fox News.

Fox News reports that Holmes is scheduled to make his initial court appearance on Monday at 8:30 a.m. local time in Centennial.

Up to 20 shots were fired in all, some penetrating the walls into other rooms, according to Fox News.

Some of those injured are children and teenagers.

Police earlier said 14 people were dead, but later revised the number to at least 12. It was not immediately clear for the reason for the revision.

Our sister station KXRM in Colorado Springs, CO, reports the youngest victim being treated at the hospital is three months old. Witnesses told them it was a horrific scene as they saw another little girl with gunshot wounds in her back being carried out of the theater. Another girl was seen leaving the theater covered in blood.

This cell phone YouTube video shows a man covered in blood being escorted out of the theater.

One witness who was in the same room as the shooter at the time of the massacre told KXRM he thought it was a prank at first as smoke filled the theater and shots were fired. He said he thought it was "some punk" lighting off fireworks when his friend sitting next to him slumped over onto his shoulder. He said he then discovered his friend had been shot in the neck.

Witness Shayla Roeder said she saw a young teenage girl on the ground bleeding outside the theater.

"She just had this horrible look in her eyes .... We made eye contact and I could tell she was not all right," Roeder said.

Police were already at the theater at the time of the shooting and arrested the suspect almost immediately. The suspect ran out of the back of the theater to his car in the parking lot where police arrested him, according to Fox News.

Police found explosives in the suspect's vehicle which has Tennessee license plates, according to Fox News.

Aurora Police Chief Dan Oates said the suspect spoke of "possible explosives in his residence. We are dealing with that potential threat," according to Fox News.

A large truck lettered "bomb squad" arrived near an Aurora apartment complex where the suspect is believed to have lived, about four miles from the theater. Dozens of police squad cars, vans and other vehicles were already at the scene, along with black-clad officers carrying automatic weapons.

Police evacuated residents of the building.

Oates said bomb technicians are determining how to disarm flammable or explosive material in the third-floor apartment. He says police could be there some time, according to Fox News.

Oates says pictures from inside the apartment are fairly disturbing and the devices look to be sophisticated. FBI agents and police used a hook and ladder fire truck and put a camera at the end of 12-foot pole inside Holmesâ?? apartment, which is about four miles from the theater, according to Fox News.

Police are asking anyone with information on the suspect to call Aurora police at (303) 627-3100.

The Associated Press reports the Paris, France premier of "The Dark Knight Rises" has now been canceled.

Aurora is on Denver's east side and is Colorado's third-largest city with 327,000 residents. It is home to a large Defense Department satellite intelligence operation at Buckley Air Force Base, as well as The Children's Hospital, the University of Colorado Hospital and a future Veterans Affairs hospital.

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(FOX News and the Associated Press Contributed to this report).