The crash happened just before 3 p.m. in the 2200 block of Second Avenue in Seattle's Belltown neighborhood.
Det. Jeff Kappel with Seattle Police says a man driving a Volvo crashed into a parked Mazda as a postal worker was standing at the back of his post office van. The impact sent the Mazda into the van, pining the postal worker between the two vehicles.
The driver then backed up but as he tried to drive away, a 17-year-old girl who saw the crash ran toward the Volvo and yelled at the driver. He managed to drive away but as he left, the girl got caught on the Volvo and was knocked down, injuring her hip, Kappel said.
The man continued south on Second Avenue toward Blanchard Street, but just south of the intersection a witness in a pickup truck boxed in the fleeing driver and held him until officers could arrive.
The driver was then arrested for investigation of driving under the influence of alcohol and/or drugs, Kappel said.
The injured mail carrier was rushed to Harborview Medical Center in Seattle with leg injuries and was listed in stable condition. The girl was also taken to Harborview for her hip injury.