“Nazis are not fucking welcome at a Dropkick Murphys show.”

That was the message shouted into the microphone during the recent St. Patrick’s Day concert in New York City by the Boston Irish punk band’s bass player and singer Ken Casey, after he beat up a skinhead who was doing the Nazi salute on stage.

After 50 or so concertgoers made their way onto the stage during a performance of “Skinhead on the MBTA” (not to be confused with the Kingston Trio’s 1950s folk ballad “Charlie on the MTA”), a skinhead started doing the Nazi salute as the band broke into AC/DC’s “TNT,” reports Rock Off.

Upon noticing, Casey “ran right over to the guy, smashed him in the face, took off his bass and hit him with that and then jumped on him and all-out chaos ensued,” relays Rocks Off. “We could only assume from our vantage point that said [Nazi] got his ass kicked.”

A video of the event, which was posted to YouTube and published on Gawker, has since been taken down, labeled private.

According to a new report by the Southern Poverty Law Center (SPLC), Neo-Nazi, Ku Klux Klan and White Nationalist groups have seen an 800 percent growth since 2008, with more than 1,000 chapters of various hate groups currently existing across the United States.

The SPLC lists active chapters of Aryan Terror Brigade both in New York and here in Massachusetts, and chapters of Volksfront in Connecticut and Massachusetts as well.•