A Boston Bruins fan says he was beat up and called homophobic slurs at an Avalanche game in Denver last week ... and cops have confirmed to TMZ Sports they're now investigating it all.
Caiden Shaw told ABC 7 the interaction with Colorado fans at Ball Arena following the Bruins' loss to the Avs on Jan. 26 began innocently ... but then he claims it soon got heated.
Shaw said three men approached him ... and after some words, they began to make inappropriate comments about his sexuality.