The Los Angeles Fire Department received a medical call shortly before 11:30 a.m.
Fire officials confirmed that a 25-year-old woman was transported to a local hospital. Police and fire officials have yet to confirm the identity of that woman.
But multiple sources told ABC News that Lovato is being treated at Cedars-Sinai Medical Center. Her condition is unknown.
Lovato, who is 25, has been outspoken about her battles with bipolar disorder and substance abuse.
In March, the singer retweeted a post of an interview she gave, during which she said she was six years sober.
In May, she tweeted that new music and lyrics would reveal the truth.
Just last month, Lovato released a new song called "Sober," which includes lyrics indicating she was not sober anymore.
According to Lovato's website, upcoming tour dates have been rescheduled. The singer's publicists have not responded to Eyewitness News' requests for comment.
Fellow musicians and celebrities, including Ariana Grande, Brad Paisley and Ellen DeGeneres began taking to Twitter, showing an outpouring of support for Lovato.
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