A tour by the band Bright Eyes that has led fans to express concern over the erratic behavior of frontman Conor Oberst reached its most provocative point yet Sunday night, as the singer was described as taking leave of the music after just a song and a half. The remaining musicians invited fans onto the stage to fill in, karaoke-style, for a number of tunes before the show was canceled altogether and refunds offered.

The fun of the impromptu karaoke notwithstanding, the Houston concert may have represented a nadir for a tour that has seen Oberst’s fans lament his behavior at numerous stops along the way, although other dates seem to have come off without much of a hitch.

“Conor was in awful shape,” reported one Houston fan on social media, in a reaction typical of dozens of posts coming in from concertgoers on the scene. Oberst was described as looking unsteady as he hit the stage and “only remember(ing) a fraction of the lyrics for [second song] ‘Lover I Don’t Have to Love.’ … Then Conor left the stage after the track ended and never came back. Nate (Walcott) and Mike (Mogis) did their best to try to keep the show going and apologized to the crowd multiple times. After 10-15 mins they finally brought out the rest of the band and pulled fans out of the crowd to play three songs, karaoke-style.” Following that, representatives of the venue came on stage and offered refunds, saying the show would be halted after one more karaoke number.

A journalist on the scene said she appreciated the remaining members’ attempt to close out the show on a fun, if Oberst-less, note, but was disturbed by what she saw during the singer’s brief time on stage. “This is a disaster, and I appreciate the attempt at triage, but Jesus,” tweeted Caitlin Cruz, a senior reporter for Jezebel. “Hope Conor is okay. [White Oak Music Hall] employees were such champs about an increasingly not great situation.”

A press rep for Bright Eyes said there were no plans to interrupt the tour, and that tonight’s show at the Orpheum Theater in New Orleans will go on as scheduled.

Another attendee in Houston, author Holly Lyn Walrath, tweeted that Oberst sang “sang the second song halfway and walked off, clearly everyone in the band confused. I hope he’s okay. I’ve been to a ton of shows and never seen this. … Truly shocked.”

Rather than be angry, though, most of the fans at this show — and others along the tour that have seen Oberst indulge in alarming commentary or behavior — have expressed sympathy for the singer, acknowledging an awareness of troubles he has dealt with in the past and may be coming up against again now.

But some are wondering why those around him are not stepping in to force a lull in the proceedings.

At a Detroit show early in the tour, Oberst was described by attendees as falling off the stage in front of startled attendees in the front row. At subsequent concerts in Ohio, the singer was wearing a black brace on his left wrist and saying he had broken it during the Detroit fall. His often entertaining stage commentary has been described as sometimes cutting off introductions from the band so he could tell a five-minute-or-more ramble about subjects like his dog biting out a turkey’s eye. According to a Cleveland attendee, he said he wanted “to crucify a cat, crucify a squirrel and kill a homeless person in an alley.”

Yet at some shows, things have proceeded in a less patchwork fashion. “This makes me sad. (But) I was the Boston show and it was amazing, none of these issues,” wrote another fan, responding to reports of the reportedly shambolic shows in Michigan and Ohio.

Lorie Liebig, a journalist in Nashville who had provided reports about a recent show at the Ryman Auditorium that left her and many other attendees distressed for Oberst, tweeted after the latest reports came out of Houston: “Can everyone around Conor stop acting like this whole tour is a joke and get him some help already? Jesus.”

If there’s a hesitation to suggest the tour take a time-out, it may be because of other stops along the way where things seem to go fine. The Columbus Dispatch’s critic praised Oberst in a review of an early April show as giving a performance full of “passion and elegance… At the center of it all was Oberst, delivering his phrases like his life depended on it.”

The current tour marks the band’s first in nine years, although Oberst has toured as a solo artist during that time.

Wrote one fan in response to the news reports and alarmed social media responses from the tour, “He won’t see it, but I really hope Conor Oberst gets the help he needs. I hope he knows that people love him and love his art. I hope he knows that substance abuse is a sickness, not a defect. I hope my son gets to grow up listening to new music from his namesake for a long time.”

The U.S. tour has a busy itinerary coming up, packed with several shows a week for the next month and a half, including a June 23 stop at L.A.’s Greek Theatre, before it wraps up in Omaha July 3. From Omaha, there’s a five-week break before a European tour picks up Aug. 12 for roughly three weeks.