A detective's notes from the scene of the alleged Rihanna assault reveal disturbing details about what happened between the singer and her boyfriend Chris Brown in the early hours of Feb. 8.

According to a search warrant in the case, Rihanna, 21, read a three-page text message from a woman on Brown's phone, which led to an argument. Brown – who was charged with two felonies Thursday – allegedly tried to force his girlfriend out of the Lamborghini, and hit her head against the passenger window.

Rihanna then "turned to face Brown and he punched her in the left eye with his right hand," says the paperwork. "He then drove away in the vehicle and continued to punch her in the face with his right hand while steering the vehicle with his left hand."

According to the detective's notes taken by Det. De Shon Andrew, blood filled Rihanna's mouth. Brown, 19, allegedly told her, "I'm going to beat the s--- out of you when we get home. You wait and see!" Rihanna called her assistant and left a message saying, "I am on my way home. Make sure the cops are there when I get there." The police notes say that prompted Brown to reply: "You just did the stupidest thing ever. Now I'm really going to kill you."

The report also says that Brown bit Rihanna and put her in a headlock, and that she almost lost consciousness.

"Brown resumed punching [Rihanna] and she interlocked her fingers behind her head and brought her elbows forward to protect her face," according to the notes. "She then bent over at the waist, placing her elbows and face near her lap in attempt to protect her face and head from the barrage of punches being levied upon her by Brown."

Eventually, Rihanna began screaming for help and Brown got out of the car, according to the notes. A nearby resident heard the calls for help and called 911.

Almost three weeks after the incident, the couple reunited in Miami Beach last week.

FOX 11 in Los Angeles was first to report on the detective's notes.