Fourteen people killed in shooting at Dark Knight Rise screening in Aurora, Denver

Reports suggest that several screens within the cinema were showing the film when the attack happened, with some filmgoers initially believing the the noises were part of the film.

A person, believed to be wearing a gas mask, set off a tear gas grenade before the gunmen opened fire on the audiences.

Local radio reports suggest that police also believe there may be an explosive device in the mall's carpark.

Ambulance and police crews from across the state are attending the incident, with reports from local sources saying that police are taking the injured to hospitals in their own cars.

Fox News reports that as many as 50 people have been injured in the incident.

An eye witness who escaped from one of the theatres said he initially believed it was publicity stunt, until the gunmen threw the smoke grenade.

"I felt something in my eyes, and I knew something was about to go badly wrong," he said.

"He started shooting into the crowd. There were children in there."

He also said he saw a baby being shot a point blank range by one of the gunmen.

One gunman is in police custody. Aurora PD chief Dan Oates said that their was no evidence of a second gunman as initial reports suggested. 

More to follow.

Main image: Getty