UPDATE #2: Sources for the LA Times claim Rihanna was the woman in the car.

UPDATE: Chris turned himself into police and was booked for making criminal threats. He has since posted $50,000 bail.

One of music’s hottest couples will be MIA from the Grammy ceremony tonight.

Nominees Rihanna and Chris Brown have both issued last-minute cancellations due to an LAPD investigation. The incident stems from an alleged assault that occurred early Sunday morning.

According to the police department, Brown and a woman were arguing inside a vehicle around 12:30 AM today. The two eventually exited the vehicle when Chris reportedly became physical with the passenger. By the time officers arrived, the singer had already left the scene. That was when the injured victim named the Brown as the suspect.

Although it’s unclear what Rihanna’s role is in this matter (the victim’s name was not released), her appearance at the 51st annual event was canceled late this evening. (She and Brown were both scheduled to perform.) When contacted, her rep offered this statement to the media: “Rihanna is well. Thank you for concern and support.”

R&B legend Al Green has reportedly been asked to help fill the telecast’s hole.