According to the sheriff's office, deputies are looking for a driver who failed to stop after one of the incidents.
According to officials, a 5-year-old boy was struck near the 3200 block of Atascocita Elm Drive. He was taken to Memorial Herman by LifeFlight.
The driver who hit the boy remained at the scene.
Another child, a 9-year-old, has minor injuries after being hit near Atasococita Elm Drive and Ferrari Street, officials said.
Deputies say the person in the vehicle fled, but returned to the scene for investigations.