The gunmen, who were in full body armour, targeted a crowded cinema hall in the city of Aurora in Colorado, a suburb of Denver, the FOX news reported quoting local police.
Several people were wounded as the hotly anticipated movie premiere turned into a carnage, it said.
It quoted police spokeswoman Cassidee Carlson as saying that "the scene is still very active and we have little information for release at this time."
A bomb disposal squad had been sent to the scene of shooting. Further details are awaited.
