An Earth, Wind & Fire concert was postponed at San Francisco’s Chase Center on Thursday night after a medical emergency involving someone in the band. The person was not identified, leaving both their condition and the status of the remaining tour dates uncertain.

The group had been scheduled to perform with Lionel Richie on August 6 as part of their 26-city co-headlining tour. In a statement posted on Instagram, Earth, Wind & Fire said the show could not proceed and would be rescheduled, with a new date to be announced.

“We sincerely apologize for the unexpected change and appreciate everyone’s understanding,” the band said.