Jane’s Addiction’s reunited concert in Boston ended early on Friday after singer Perry Farrell punched guitarist Dave Navarro onstage in the middle of a song.

As video footage from the show revealed, during a performance of “Ocean Size” Farrell became agitated for some unknown reason, walked up to Navarro and rammed his shoulder into the guitarist’s back. An aggressive and still angry Farrell then continued to yell at the stunned Navarro, with the singer eventually landing a right hook on his old bandmate’s shoulder:

“What the fuck?” Navarro wondered as a crew member held Farrell back; when the singer tried to sidestep the crew member and overwhelm Navarro again, two more crew members and even bassist Eric Avery ran over to restrain Farrell and escort him backstage. Navarro eventually left the stage as well, and the concert ended after 11 songs, three or four songs fewer than a typical show so far on the now-threatened Jane’s Addiction reunion tour.

According to VarietyWhatever was happening between the band members onstage in Boston, it had been simmering since the “Core Four” lineup’s first tour in 14 years kicked off in August. At previous stops, Farrell’s long-winded banter with the audience had left Navarro visibly frustrated onstage. Variety also notes that several concert reviews noted that Farrell drank a bottle of red wine onstage during the performance.

However, none of the early incidents — including a pair of troubled shows in New York City earlier in the week — predicted what happened in Boston: JamBase reported that the trouble began during “Mountain Song,” when Farrell yelled at Navarro. The bickering continued into the next song, “Three Days,” and culminated in the “Ocean Size” punch.

Jane’s Addiction has yet to comment on the confrontation, and Avery’s Instagram — which posted regularly while the band was on tour — has not mentioned the incident. However, Farrell’s wife Etty wrote a lengthy explanation on social media detailing the situation.