The Voice' singer Christina Grimmie shot dead in concert

Miami — Singer Christina Grimmie, who starred in NBC's "The Voice," was killed after being shot at a concert in Orlando, Florida by an unidentified gunman, who then killed himself, police said Saturday.

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

The 22-year-old Grimmie performed late Friday with the group Before You Exit at Orlando's Plaza Live Theater and stayed after to sign autographs and sell merchandise.

A man, who was armed with two guns, walked toward her and shot her, police said.

"Christina's brother immediately tackled the suspect, who shot & killed himself," the police said.

Grimmie was rushed to the Orlando Regional Medical Center.

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 spokeswoman Wanda Miglio said at a news conference.

"This is a very tragic event. 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 not hurting anyone else," Miglio said.

The shooting seemed likely to add fuel to the long simmering debate over gun laws in the United States, where guns were used in more than 11,200 murders in 2013, according to the Centers for Disease Control and Prevention.

But past bouts of even more extreme gun violence, including the 2012 killing of 20 school children at an elementary school in Connecticut, have led to little change in a country where the right to bear arms is protected under the second amendment of the US constitution.

US Democratic candidate Hillary Clinton has vowed to take on the powerful US gun lobby if elected president, while Donald Trump, the presumptive Republican nominee, has promised "to cherish the Second Amendment".

'We are heartbroken'

Grimmie, who competed in the sixth season of "The Voice" in 2014, released her debut EP "Find Me" in 2011.

"We are heartbroken," the NBC talent show said on its Twitter account after the shooting, calling the young singer "a loved member of our family".

"There are no words. We lost a beautiful soul w/ an amazing voice," it said after her death was confirmed.

Adam Levine, the singer whose team she performed with on the program, posted a picture of himself with her on his Instagram account after the incident when the singer was taken wounded but still alive to the hospital.

"I'm sad, shocked and confused. We love you so much Grimmie. We are all praying hard that you can pull through this... this just isn't fair," he wrote, before news of her death became public.

Fans posted video clips on social media of her performances, including her cover of Miley Cyrus's "Wrecking Ball" during a blind audition on "The Voice".

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