A police spokesman says the gas mask-wearing suspect arrested in connection with a mass shooting in the Denver suburb of Aurora is a man in his early 20s.
Aurora police spokesman Frank Fania told ABC's "Good Morning America" that investigators don't believe anyone else was involved.
Aurora Police Chief Dan Oates says witnesses reported the person released some type of a canister, then they heard a hissing sound and saw a gas - and then the gunman started shooting.
Officers found the suspect near a car behind the theater and also located a gas mask, rifle, handgun and at least another weapon.
The suspect's name hasn't been released and police haven't indicated if there was a motive.
