Officers investigating her disappearance chased Conway after he drove past the girl's house later that morning.
Gundlach says Conway crashed into a truck and fought with police, who used a Taser to subdue him.
The girl, whose name was not released, was found in the trunk and hospitalized for a possible spinal injury.
Police say Conway, who is listed on the state's sex offender Web site for rape, was taken to a Modesto hospital and would be booked into Stanislaus County Jail.