3 Ninjas Knuckle Up (1995)

During their summer vacation, Rocky (Michael Treanor), Colt (Max Elliott Slade) and Tum Tum (Chad Power) visit their grandfather (Victor Wong), who is training them to be martial arts masters. They soon befriend Jo (Crystle Lightning), a Native American girl who lives nearby. When Jo's father goes missing, the boys realize this may be connected to revelations that a high-profile businessman (Charles Napier) has been secretly dumping noxious waste in a sacred burial ground.