MIAMI • Singer Christina Grimmie, who starred in NBC's The Voice and has performed in Singapore, died yesterday after being shot at a concert in Orlando, Florida, by a gunman who then killed himself.

"With deep regret, we have confirmed Christina Grimmie, @TheRealGrimmie, has died from her injuries," the Orlando Police Department said on its Twitter account, reported AFP.

The 22-year-old had performed with the group Before You Exit at Orlando's Plaza Live Theatre on Friday night and stayed on after the show to sign autographs and sell merchandise. A man, who was armed with two guns, walked towards her and shot her, the police said, adding: "Christina's brother immediately tackled the suspect, who shot and killed himself."

Grimmie was taken to the Orlando Regional Medical Centre. Police confirmed her death at 3am yesterday (3pm Singapore time), reported The Orlando Sentinel. The motive of the gunman, who was not identified, was unclear.

"We don't know if he was just a crazy fan that followed her on Twitter or on social media. We really don't know," police spokesman Wanda Miglio said at a news conference, reported AFP. "This should have been something that was fun and exciting, and for something like this to happen is just a tragedy."

She said about 60 to 100 people attended the concert, but only a handful were left when the shooting occurred.

"Her brother is a hero for saving and stopping him from hurting anyone else," Sgt Miglio said.

Fans and musicians Grimmie worked with were shocked and tributes poured in for the singer.

The National University of Singapore sent its condolences as well: "Shocked & sad. Christina sang at NUSSU Rag 2015. Thoughts & prayers with her family, friends & fans. #RIPChristina."

The Hashtags #RIPChristina and #PrayForChristina were both trending on Twitter yesterday.

A New Jersey native, Grimmie first gained public attention with moving covers of hit songs in videos viewed by millions on YouTube.

Even before appearing on The Voice, she had more than three million followers on her YouTube channel, zeldaxlove64.