Media sources in the US are reporting that up to 14 people have been shot dead at the premiere of The Dark Knight Rises in Denver.

Firefighters and police have swarmed a mall after an incident during a premiere screening of the Dark Knight Rises.

A radio host has already spoken and suggested that victims were shot dead, although other outlets claim there may have also been an explosion.

Brenda Stuart, of 850 KOA Radio, also said police are looking for a second explosive device at the movie theatre.

Initial reports from emergency services indicate there could possibly be 30-40 people injured, and have requested all ambulances in the area to respond.

Witnesses say someone wearing a gas mask opened fire on the moviegoers and set off some sort of smoke or gas bomb.

While a suspect has reportedly been detained, investigations are continuing.