The Town of Waukesha Fire Department and the Waukesha County Sheriff's Department responded to the crash at 12:15 a.m. Wednesday, according to a news release.
The woman, who was the only person in the vehicle, was pronounced dead at the scene, according to the Waukesha County Sheriff's Department. Authorities have not yet released her identity.
"The initial investigation indicates the car was traveling northbound on Merrill Hills Road and after cresting a hill, it appears the driver failed to negotiate the slight right curve and crossed the southbound lane then left the roadway and struck the large tree," states a news release from the Waukesha County Sheriff's Department.
The accident remains under investigation. It is unknown if other factors contributed to the crash, according to authorities.