The ambulance was transporting a victim to the hospital when the accident happened at 6:54 p.m. on Franklin Avenue in Valley Stream.
Police said the car had gotten into another accident on Franklin Avenue near Corona Avenue in Franklin Square.
After leaving that scene, the driver headed southbound on Franklin until crashing into the ambulance near Emerson Place in Valley Stream.
No one was seriously injured in either accident.
The victim in the ambulance was being transported from an assisted living facility to Franklin General Hospital.
Police arrested the driver of the car at the scene. Charges were pending.