Nicki Minaj and Cardi B were involved in an altercation on Friday night, US time, that got physical at a New York Fashion Week party and left Cardi B with a mark on her head.
A person who witnessed the incident, speaking on condition of anonymity, said Minaj was finishing up a conversation with someone when Cardi B tried to attack her, but Minaj's security guards intervened.
Video circulating on social media shows Cardi B lunging toward someone and being held back at the Harper's Bazaar Icons party. Cardi B reportedly threw one of her shoes at Minaj. Another video shows Cardi B being escorted out of the event by security.
Cardi B, wearing a voluminous red Dolce & Gabanna gown, was seen leaving the party with what appeared to be a bump on her head. She was barefoot.
She and Minaj have been rap rivals since Cardi B began achieving huge success over the past year.
Both women have been regulars during the first few days of fashion week, with Cardi B sitting front row with Vogue editor-in-chief Anna Wintour and actor Tom Hanks at the Tom Ford show on Wednesday night.
In a post on Instagram Cardi B didn't call out Minaj by name but alluded to the fight and said she was sparked because her mothering skills were being disparaged. She and rapper Offset recently had their first child together, a girl.
"I've let a lot of s--t slide! I let you sneak diss me, I let you lie on me, I let you attempt to stop by bags, f--k up the way I eat!" Cardi wrote. "You’ve threaten [sic] other artists in the industry, told them if they work with me you'll stop f---in with them!! I let you talk bug s--t about me!! I addressed you once in person, I addressed you a second time in person, and every time you copped the plea!!
"But when you mention my child, you choose to like comments about me as a mother, make comments about my abilities to take care of my daughter is when all bets are f--kin off!! I've worked too hard and come too far to let anybody f--k with my success!!!!"
Offset made headlines when he walked for Jeremy Scott in his show on Thursday night.
Minaj has not yet commented on the incident.