Bebe Rexha, a popular singer, was taken off stage during a concert on Saturday after being struck in the head by a phone that a fan had thrown.
When the object struck the star on the side of her head while she was performing in New York, she fell to her knees.
Later, as she was being escorted from the location, she had her hands pressed to her face and appeared to be in pain.
Fans shouted "that's assault" as they watched a man being removed from the crowd in a video that was posted online.
The singer, whose hits include "Meant to Be" and "I'm Good (Blue)," has not yet commented on the situation.
Her mother was cited by the gossip website Pop Base as saying that the celebrity sought medical attention and required three stitches.
Rexha's team has been contacted by the BBC for a response.
The celebrity was finishing up her performance at Pier 17 in New York when the incident took place.
She had already performed I'm Gonna Show You Crazy with an emotional fan from El Salvador and played Seasons on the spot in response to an audience member's request.
Fans who came to the show expressed their shock at how it ended.
Two hours later, one person tweeted, "I'm still in shock.". I witnessed something fly and strike her. Up until I saw the drop, I assumed it was a CD or piece of paper. ".
Another person said, "This old man ruined everything. People were really dressed up and in a good mood because they were going to a concert.
Third: "Super unsettling ending to an otherwise great show.". "I really hope she's ok,".
Fans throwing their phones onstage in the hopes that performers will take a selfie and take them back is becoming more and more common.
Even leaving voicemails for the owner's friends on their phones has been known to happen to Harry Styles.
But while performing in Los Angeles, he was struck in the eye by a handful of Skittles, and he had to spend the rest of the show rinsing it out with water.
At one of the band's reunion shows in Glasgow, N-Dubz star Tulisa had her sunglasses knocked off by a fan's phone.
In 2004, after being struck in the eye by a lollipop, David Bowie reportedly made the decision to stop touring.
The hard candy, which the locals call "love on a stick," was probably thrown out of love, but it hurt the singer a lot.
Before returning to the microphone and cursing at the offender, he backed off the runway, hunched over, and received help from his set crew.
He said: "The other one has just become a little bit more decorative than it was before... Lucky you hit the bad one. After a childhood fight, I only have one good eye.".
When he regained control, he declared that he would punish the crowd by performing an "even longer concert" than scheduled.
He jokedly asked if anyone had been hit in the eye after tossing a guitar pick into the audience toward the end of the performance.
