An early morning hit-and-run crash on Washington Pike has killed a pregnant woman and a Good Samaritan who assisted her.

Two women stopped at a man's house on the 4200 block of Washington Pike to ask for help after their vehicle ran out of gas, Knoxville Police Department spokesperson Darrell DeBusk said.

Nelson A. Soto, 45, answered the knock and helped the women. Soto's son told 10News that his father had just gotten home from work, so he was still awake. He put gas from a gas can he had at the home inside the car.

When Soto was done, the women hugged him to thank him. At that moment, a speeding Ford Expedition heading east hit Soto and one of the women, Chasity E. Thornell, 24, of Millertown Pike. Both were declared dead at the scene.

Emergency responders discovered Thornell was seven months pregnant. Thornell's baby also died. Thornell leaves behind a 19-month-old daughter, Ava.

The woman who was with Thornell was not hit.

Police are looking for the driver of a silver or white Ford Expedition. The suspect is described as a tall, white male with a slender build, who may be in his 20's. The vehicle would have front end and passenger side damage.