A Rascal Flatts concert was hurriedly evacuated in Noblesville, Indiana, on Thursday after an expected encore from the country-pop trio failed to materialize.

Venue officials from the Ruoff Home Mortgage Music Center referred questions about the evacuation to local law enforcement. Hamilton County Sheriff's spokesman Bryant Orem told IndyStar an "open investigation" is underway with no details available Friday morning.

The following message was posted at the Rascal Flatts Facebook profile at 10:35 a.m.:

"Indianapolis - Due to a security concern at the show last night, standard procedures were quickly executed and everyone was able to safely leave the building. The safety of our fans, band and crew is always the top priority for us, so we are so thankful for everyone who jumped into action and for your understanding. We will be back soon!"

Several fans expressed disappointment via social media about the show's abrupt end. At least two Rascal Flatts signature songs — "God Bless the Broken Road" and "Life is a Highway" — would have fit within the 15 minutes remaining before Thursday's 11 p.m. curfew.

According to attendee Britni Sherlock, an announcement via the public-address system declared the show to be over following an otherwise standard break in which fans cheered to coax the musicians back onstage after the main set.

"Everyone boo’d," Sherlock told IndyStar. "We continued to wait in the pavilion, and that’s when security came up to everyone and told us to leave. I asked what was going on and he replied, 'We were told to evacuate the pavilion immediately.' "

Attendee Andy VonDielingen said he witnessed a disruption in the general-admission "pit" area closest to the stage.

"(Rascal Flatts) had just finished their song 'Banjo' and did the what-was-thought-to-be-false 'Good night' before the encore," VonDielingen told IndyStar. "Their piano player started to play and then just stopped and left. A few minutes later lights come on and security is pulling some guy looking to be in his 20s out of the pit ... Everyone is standing around, looking at each other and wondering what is going on."

Rascal Flatts, playing a date of the trio's "Back to Us" tour with supporting acts Dan & Shay and Carly Pearce, made no post-show statements via social media.

The group, known for 12 No. 1 hits on Billboard magazine's country chart, served as opening act for the Rolling Stones at Indianapolis Motor Speedway in 2015.

Ruoff Home Mortgage Music Center is scheduled to host a double-bill performance of Jeff Beck and Paul Rodgers Friday.