(AP) WASHINGTON - A federal law enforcement official said the semi-automatic assault rifle used in the deadly Colorado movie theater shooting jammed during the attack.
The official said late Saturday the rifle had a high-capacity ammunition magazine which, based on witness accounts and evidence collected at the scene, apparently jammed.
The rifle's malfunction then forced the suspected shooter, James Holmes, to switch to another weapon.
The official spoke on condition of anonymity to discuss the investigation.
Aurora Police Chief Dan Oates has said a 100-round drum magazine was recovered at the scene of the shooting in suburban Denver. Oates said such a weapon was capable of firing 50 to 60 rounds a minute.
Police said Holmes also had two Glock pistols and a shotgun.
Holmes, a 24-year-old former graduate student, is in custody. The attack early Friday killed 12 people and wounded nearly 60 others.