British singer and producer Devonté Hynes, known as Blood Orange, said on Friday that security personnel assaulted him and his girlfriend after a performance at Chicago's Lollapalooza.
Hours earlier, Hynes had given a speech against racism and police brutality from the festival's stage.
The day of the alleged assault, Hynes was wearing a homemade T-shirt emblazoned with the names of victims of police brutality and racist violence.
Hynes' girlfriend, Samantha Urbani, took to Twitter to compare the assault to a recent case of alleged police brutality in New York.
Eric Garner, a Staten Island resident and father of five, died last month while police officers tried to arrest him for selling loose cigarettes. The city corner ruled Friday that Garner, who was African American, was chocked to death by one of the officers.
Urbani later tweeted that she had learned the security guards in question were not Lollapalooza staffers, but outside contractors.
She appears to have since deleted the tweet, but Pitchfork kept a quote of the original message.
"After talking w lollapalooza ppl we've discovered the guards who assaulted us were NOT lolla staff, but privately hired for that stage," the website reported Urbani as tweeting.
Hynes' supporters flooded the festival's Facebook and Twitter pages with complaints against the alleged behavior of the security guards.
Lollapalooza eventually responded with a statement to Pitchfork acknowledging "an incident."
"Late Friday night, we learned of an incident involving an artist and a security guard on site," the statement read. "Since then, we have been in contact with those involved and the authorities, as we work together to resolve the situation. As always, our top priority is to ensure the safety of everyone at the festival."