Bollywood megastar Amitabh Bachchan expressed shock over the news of the mass shooting incident at the midnight premiere of the new Batman movie "The Dark Knight Rises".

A man opened fire at a theatre in suburban Denver Friday, killing 12 people, and leaving many others wounded.

The suspect reportedly claimed to be the fictional archenemy of Batman during the investigation and told police he was "the Joker".

"Each day something disturbing appears. Saw live footage of Colorado killings... gunman dressed as Batman saying he was 'the Joker', " Big B tweeted.

The man had a rifle, a handgun and a gas mask when police arrested him. The incident has shocked people across the world and Indian celebrities, including actress Madhuri Dixit, who stayed in Denver after her marriage in 1999, and jewellery designer Farah Khan Ali, have condemned it.

"My heart goes out to the families, " tweeted Madhuri.