The star, 28, was rear-ended in her Land Rover by a paparazzo driving a Jeep Cherokee in Beverly Hills just before 2 p.m. on Monday, Lt. Tony Lee told Us.
"She complained of pain," he said, adding that she refused medical care at the scene but would "seek her own medical treatment."
According to a witness, Richie went to L.A.'s Cedars-Sinai Medical Center with her mother to be treated for minor injuries.
The driver who rear-ended Richie was arrested and charged with driving without a license, and was in the process of being "physically booked," Lee told Us. Police were still trying to verify his identity. A police spokesperson could not confirm if anyone was speeding but said that they weren't at a traffic light or intersection. "This will likely be a misdemeanor traffic violation, and the photographer's vehicle will be towed," Lt. Lee added.
An unnamed adult was a passenger in Richie's car, but her two children (Harlow, 20 months, and Sparrow, born Sept. 9) were not in the vehicle at the time of the incident.