Amber Tucker, 17, and Brandi Murrah, 16, are still at large after police found the vehicle in Harrodsburg, Ky.
John Hodgkin, public information officer for the Department of Juvenile Justice, said one of the girls feigned sickness, telling the driver that she was going to throw up. The driver slid open the plastic divider to allow more air conditioning to reach the girl when the other girl reached over and began to strangle the driver with her handcuffs, Hodgkin said.
Both girls were secured with handcuffs and belly-chains, which are meant to restrain the hands to the body, he said.
While choking the youth worker, one of the suspects was able to wiggle her way into the front seat where she continued to choke the woman, who is in her late 40s or early 50s, and threw the car keys to the other girl so she could get free, police said.
The two girls then threw the driver out on the road and drove away in the vehicle.
The car was found at 2:41 a.m. yesterday morning with no one in it, police said. The vehicle was a government-issued Ford Crown Victoria and was found by an officer on routine patrol.
The female youth transporter was not seriously injured and was released from the hospital after receiving treatment for bruises on her neck.
Hodgkin said the girls originally were in custody for misdemeanor charges that would not be thought to be violent.
"They were not considered dangerous," he said. "There was no reason to believe that they would be a threat to the driver."
Hodgkin also said that there is no reason to believe the girls are armed. The transporter was not armed and was not trained in weaponry, unlike the adult system of justice.
The girls were being transported from Warren County to the Morehead Youth Development Center.
If the girls are caught, they will return to a detention center and will face new, more serious charges, Hodgkin said.
Hodgkin said that state police believe the girls may be heading towards Russellville, Kentucky, a town near where one of the girls lives.