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)

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.

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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.