A gunman opened fire at a Florida concert venue as singer Christina Grimmie signed autographs for fans after a show, killing the onetime star of "The Voice" before shooting and killing himself, officials said Saturday.

Orlando Police Chief John Mina said at a news conference that the gunman traveled to Orlando specifically to attack Grimmie.

The suspect, identified as a 27-year-old white male, didn't appear to know Grimmie personally, Mina said. He may have been a deranged fan, although the motive was still unknown.

Grimmie was shot to death after giving a concert in Orlando on Friday night. She died early Saturday.

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The 22-year-old singer from New Jersey finished third during season six of NBC's "The Voice" in 2014, competing on the team of Maroon 5 star Adam Levine. She began amassing a following on YouTube as a teenager, gripping online viewers with her powerful renditions of hit songs. Her videos on YouTube have garnered millions of views.

In an earlier statement, police said Grimmie had performed with the band Before You Exit at The Plaza Live in Orlando. The concert ended around 10 p.m., and Grimmie was shot as she signed autographs for fans at a merchandise table.

Grimmie's brother immediately tackled the gunman, who then shot and killed himself during the struggle, police said. They credited the singer's brother with preventing the gunman from hurting others.

No off-duty officers were working the concert, Mina said. The venue uses security guards who are unarmed and has no metal detectors.

Sgt. Wanda Miglio said that about 60 to 100 people were in attendance, though only a handful remained when the shooting happened.

Grimmie had posted a video of herself shortly before the concert was scheduled to begin, encouraging fans to come see her perform.

ORLANDO!! Come out to the show tonight at the Plaza Live! Starts at 7:30!😎 pic.twitter.com/0D4mNupCTi — Christina Grimmie (@TheRealGrimmie) June 10, 2016

Levine posted a photo of himself with Grimmie on Instagram, commenting before her death was confirmed:

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. A photo posted by Adam Levine (@adamlevine) on Jun 10, 2016 at 11:35pm PDT

He issued a statement later in the day.

"Behati and I are absolutely devastated and heartbroken by Christina Grimmie's tragic death," Levine said, referring to his wife, Behati Prinsloo. "Our hearts go out to her family. Christina was a natural, a gifted talent that comes along so rarely. She was taken from us too soon. This is yet another senseless act of extreme violence. I am left stunned and confused how these things can conceivably continue to happen in our world."

When reports of Grimmie's death first surfaced, #PrayforChristina was the top trending hashtag on Twitter. After her death was confirmed, #RIPChristina became the top trending hashtag as Grimmie's fans took to social media to express an outpouring of grief.

"The Voice" paid tribute to Grimmie on its official Twitter page:

There are no words. We lost a beautiful soul with an amazing voice. Our hearts go out to the friends, fans and family of @TheRealGrimmie. — The Voice (@NBCTheVoice) June 11, 2016

The Philadelphia Inquirer reported in 2014 that Grimmie moved to Los Angeles in 2012 after joining Selena Gomez on tour to focus on her singing career.

"I'm done being surprised by cool things she does. She's very talented and she's worked incredibly hard - it's a dangerous combination," her brother Mark Grimmie told the newspaper at the time.