BURBANK (CBSLA) — A fight involving some kind of weapon broke out Tuesday night at a showing of “Joker” in Burbank.

The fight was first reported at about 9 p.m. inside theater 15 at the AMC Burbank, 125 E. Palm. When police arrived, they found a man upstairs with an injury from some sort of glass to the head.

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(credit: CBS)

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Police say they believe as many as nine people were part of the fight, which involved some sort of weapon. But the other eight people took off before officers arrived.

Burbank police investigators are looking at the theater’s security video and are also trying to speak to witnesses to piece together what happened.

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Across the country, there has been extra security at showings of the film after threats of a potential mass shooting surfaced online.