Authorities said 34-year-old Jamie Arsaga of Clayton got out of the van to check the mail Thursday afternoon, and allowed her daughter to move into the driver's seat while it was parked inside their garage.
They said the child mistook the gas pedal for the brake and ended up pinning her mother under the garage door after she tried to grab the mirror to stop the van.
Arsaga was seriously injured, but is expected to survive. Her 8-year-old daughter was not hurt.
No charges have been filed.