At least 10 people were killed and 30 to 40 others injured when a masked man opened fire at the premiere of new Batman movie The Dark Knight Rises at a theater in Denver.

The gunman opened fire at the movie cinema complex in Aurora, where three theatres had a midnight showing of The Dark Knight Rises, Reuters reported citing local news media.

The shooter was also believed to have set off a smoke or teargas bomb.

An NBC News report said one suspect was in custody.

Details are awaited.