According to the Grant County Sheriff's Office, the vehicle the suspects were driving was found in Chelan, but Rebecca Basil has still not been located.
The Washington State Patrol has issued an AMBER Alert for a 14-year-old girl.
According to WSP, 14-year-old Rebecca Basil and her 9-year-old brother left their parent's condo in Chelan on Tuesday, taking their parent's car without their knowledge.
The two drove to Malott, Washington and an unknown woman and man joined them in the car.
On Wednesday, the 9-year-old boy was dropped off at the family condo in Chelan around 5 p.m. but Basil remains with the unknown man and woman.
Their destination is not known, however, Spokane was mentioned.
Basil is described as having brown eyes, long black straight hair, 5 feet 9 inches tall, and 120 pounds.
She was last seen wearing a dark green Carhart hoodie with light blue jeans.
The last known car they were driving in a silver 2015 Subaru Legacy with Washington plate number BJU3169.