AceShowbiz - Authorities were called to the AMC Burbank 16 theatre in California on Tuesday, October 15 night when a fight broke out during a screening of "Joker".
Several fire trucks and police vehicles were seen outside the cinema after receiving calls that four people were fighting inside the venue.
A Burbank police spokesperson told The Hollywood Reporter there was no active fight when officers arrived at the scene, and that they located one man who suffered a head injury.
Police believe a glass bottle may have been used in the attack, although that has yet to be determined, and they are investigating the incident as an assault with a deadly weapon.
No arrests have been made as yet, and the investigation is ongoing.
The incident comes after leading man Joaquin Phoenix stormed out of an interview with Britain's Daily Telegraph after he was confronted with a question about whether he worries his performance as Batman's twisted nemesis will "inspire" violence.
The star later returned and explained he panicked because he'd never thought of the possibility before. However, he was previously asked a similar question by IGN, to which he responded: "I don't think it's the responsibility of a filmmaker to teach the audience morality or the difference between right or wrong."