Cardi B postponed her Indianapolis concert at Bankers Life Fieldhouse over safety concerns after a security threat, the rapper said Tuesday night.

"Dear Indiana people I'm so sorry for today," Cardi B tweeted late Tuesday night.

She wrote that she was at the arena and had even rehearsed a new move she was excited to do during her show.

"Unfortunately there was a security threat that is currently under investigation right now," she wrote. "My safety and your safety first."

Her tweet included a short video showing soundcheck preparations for the show. Cardi B also posted the video on Instagram. The video was timestamped 4:26 p.m. and tagged as being recorded in "Indianapolis -- Wholesale District."

"Dear Indiana I just want to let you know I was in the venue today," she wrote. "I rehearsed and started doing glam."

In her post, she thanked the promoters, saying the concert was already rescheduled.

"Im so sorry guys I never dealt with a situation like this before and I’m not taking any chances," she wrote.

Cardi B concert rescheduled for Sept. 11

Bankers Life Fieldhouse announced that the rapper's sold-out show has been rescheduled for Sept. 11. Security told concertgoers waiting in line outside the arena shortly before 6:30 p.m. that the show was postponed.

In a statement issued at 6:50 p.m., the arena cited "circumstances beyond anyone’s control" for the postponement.

The concert's promoter, Kansas-based Mammoth Live, issued a similar statement: "Due to a security threat and safety concerns at this evening's show, management has advised that this show be postponed. These threats are currently under investigation."

IMPD said they were "notified of an unverified threat to the artist" and said an investigation is ongoing. There is no immediate threat to public safety, police said.

According to multiple police officers and security, the Grammy-winning rapper had been in Bankers Life Fieldhouse for a soundcheck prior to the postponement.

After the postponement, WHHH-FM (96.3) on-air personality B-Swift said he was told Cardi B was present at the arena earlier in the day. Supporting act Saweetie made a promotional visit to WHHH on Tuesday.

Saweetie and fellow supporting act Kevin Gates were expected onstage between 7 and 9 p.m., with Cardi B to follow.

'We're really bummed'

Alexis Walker told IndyStar she drove six hours from Toledo, Ohio, to see the Indianapolis show. She and the woman she was with found out the show was not happening 15 minutes before it was slated to start, as they were walking out of the Hyatt hotel across from Bankers Life Fieldhouse.

"I'm not mad at Cardi B at all," Walker said. "That's my girl. We're going to meet and be best friends."

Chealsie Hampton and Victoria Scott bought tickets for the show months ago.

"We're really bummed," Hampton, who is from Fishers, told IndyStar. "This was the big thing we've both been looking forward to this week."

"It is what it is. We're going to enjoy our night out here, regardless," Hampton said.

Tickets for the July 30 date will be honored in September. If a ticketholder cannot attend the Sept. 11 show, refunds are available at the point of purchase.

According to a phone call from Ticketmaster Fan Support to a concertgoer, ticketholders who purchased online through Ticketmaster can get a refund by clicking the "refund" link on their order when they log into their account on a desktop or mobile web browser.

Indianapolis one of Cardi B's six arena shows

Bankers Life Fieldhouse was intended to be part of a six-date Cardi B arena tour amid a string of festival appearances this summer. Beginning July 23, she headlined arenas in Tulsa, Oklahoma; Wichita, Kansas; Lincoln, Nebraska; and Minneapolis. The run of indoor dates is scheduled to end tomorrow in Charlottesville, Virginia.

The makeup Indianapolis performance will fall between a Sept. 7 amphitheater show in Syracuse, N.Y., and the Sept. 14-15 Music Midtown festival in Atlanta — where Cardi B is a co-headliner with Travis Scott, Panic at the Disco, Billie Eilish and Vampire Weekend.

Cardi B previously performed in Indianapolis in April 2016, sharing a bill with Miami rapper Trina at Club Live (now Citadel Music Hall). Later that year, Cardi B performed as part of "Santa Slam" presented by radio stations WHHH-FM (96.3) and WNOW-FM (100.9) at Indiana Farmers Coliseum.

Call IndyStar reporter David Lindquist at 317-444-6404. Follow him on Twitter: @317Lindquist.

Andrew Clark is a reporter for IndyStar. Call him at 317-444-6484 or email him at andrew.clark@indystar.com. Follow him on Twitter @Clarky_Tweets.