James Amos, 23, was driving his 2008 Toyota Tacoma truck south on Muirwood Drive across Muirwood Park when the girl ran directly into the truck's path shortly after 2 p.m., police said.
Amos had been looking for a place to park and was driving about 5 to 10 mph when he struck the girl, according to police.
The girl's mother, 38-year-old Sharon Kim, was standing nearby when her daughter was hit, police said.
An emergency helicopter responded to the park, where several soccer games had to be broken up to make room for the landing, police said.
The girl was airlifted to a local hospital for treatment and her injuries did not appear to be life threatening, according to police.