The 27-year-old singer was not injured in the crash, but the driver of the car she struck from behind died, according to the California Highway Patrol.
Brandy struck her while driving her 2007 Land Rover on the northbound 405 Freeway, just south of the 101 Freeway.
No arrests have been made in the accident, and details regarding what caused the crash are unknown.
CHP spokesman Leland Tang said that there was no evidence of "wanton disregard" of safety by Brandy, and if any charge would be filed against her, it would be nothing more than a misdemeanor count.
"She wishes to publicly express her condolences to the family of the deceased," said Brandy's publicist in a statement.
Brandy was driving alone and was not under the influence of alcohol or drugs, said Tang. She also told officers she was driving at the speed limit of 65 mph before the crash.