Harley Flanagan, one of the founding members of the band, was arrested and charged Friday with assault and criminal possession of a weapon, The New York Times reported Saturday.
"They think they're going to play my [expletive] music that I helped write?" Flanagan allegedly yelled before stabbing band members William Berario and Michael Couls, who were treated at Bellevue Hospital.
Lead singer and co-founder of the band, John Joseph, said he was tipped off to the attack by threatening posts Flanagan wrote on Facebook, the New York Post reported Sunday. Joseph said he warned festival organizers, but "they didn't take that threat seriously."
"He shouldn't have been at that show," Joseph said of Flanagan. "He showed up at the show with a knife. It shows intent. He has two kids. He needs to grow up."
Joseph said the incident is the most recent incident in a long history of feuds within the band since its inception in 1981.
"This dude has been a negative thorn in the side of this band forever," Joseph told the Times. "I hope he gets what's coming to him."
Flanagan's lawyer, Sean Parmenter, said his client was acting in self-defense after he was "jumped" in "retribution" by the band members, the Post reported.