Sources: shooter took prescription drug before attack

CALL7 Investigators Obtain Information Detailing Scene Of Shooting

DENVER - First responders to the Aurora theater shooting at first thought the shooter was a fellow officer, and the shooter had taken 100mg of Vicodin about two and half hours before the shooting, according to information from sources.

James E. Holmes, a 24-year-old former grad student who police identified as the shooter, told police he was acting alone and tipped them to the booby trapped explosives in his Aurora apartment. But he then asked for a lawyer and stopped cooperating.

According to sources, he had nine clips in an ammo carrier and police found at least three .40-caliber magazines, a shotgun and a large drum magazine on the floor when they arrived.

One source believed the ammo drum for the AR-15 had jammed sometime during the shooting.

Sources describe an eerie scene with dying and wounded people on the floor, strobe lights flashing through the smoke, screaming sirens and the Batman movie playing in the background.

The incident started with Holmes in the theater watching a movie for a few minutes. Witnesses said he left and returned dressed in the body armor and tactical gear, according to sources.

He threw what appeared to be tear gas grenades and began firing three weapons -- a 12-gauge shotgun, a .40 caliber Glock pistol and an AR-15 assault rifle, according to sources.

Holmes exited the theater where he was confronted by at least two officers.

The source familar with the investigation indicated that police noted in reports that Holmes told them he took 100 mg of Vicodin.