NOBLESVILLE, Ind. (AP) – Country group Rascal Flatts abruptly ended an Indiana concert because of what police call a “security issue” that is being investigated.

Concertgoers say the band didn’t return for an expected encore Thursday night at Ruoff Home Mortgage Music Center in suburban Indianapolis, after which a public-address announcement said the show was over.

Security guards told people to evacuate the seating area. Fan Andy VonDielingen told The Indianapolis Star he saw a disruption in the general-admission area closest to the outdoor amphitheater’s stage.

The Hamilton County Sheriff’s Department said Friday the matter is an open investigation. It didn’t immediately release any details.

Rascal Flatts said on Twitter that everyone was able to leave safely and thanked fans for their understanding.

Copyright 2018 The Associated Press.