Authorities in Denver, Colorado have evacuated the area surrounding a cinema where a gunman opened fire on moviegoers.

A police bomb disposal robot checked a vehicle in the multiplex's car park, believed to belong to the suspect, for any explosive devices.

The masked gunman opened fire on cinemagoers at a showing of new Batman film Dark Knight Rises in the early hours of Friday, police said.

Denver's KOA radio station said the man set off a tear gas bomb inside a mall in the suburb of Aurora before the shooting erupted.

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