Gunman's weapon 'had jammed'

The semi-automatic assault rifle used in the deadly Colorado cinema shooting jammed during the attack, a federal law enforcement official has revealed.

The official said the rifle had a high-capacity ammunition magazine and that it jammed, forcing suspect James Holmes to switch to another weapon.

Aurora police chief Dan Oates has said a 100-round drum magazine was recovered at the scene of the shooting in suburban Denver. He said such a weapon would be able to fire 50 to 60 rounds a minute.

Police say Holmes also had two Glock pistols and a shotgun.

Holmes, a 24-year-old former graduate student, is in custody. The attack early on Friday killed 12 people and left nearly 60 others injured.