Mesa police have arrested a woman on suspicion of running over a 3-year-old boy with her truck and driving away.

The boy was riding a tricycle on a Mesa sidewalk just after 3:30 p.m. Saturday. As he crossed a driveway, the woman backed over him, police said.

Police said the boy's father, who saw the incident, ran to the truck and pounded on the windows to stop the driver. But she drove away.

The boy was airlifted to a hospital with severe head injuries and was in serious condition.

The woman, identified as 28-year-old Heather Funk, was picked up shortly after the incident when patrol officers spotted her truck driving on a nearby road.

Funk was booked on suspicion of aggravated assault, driving under the influence of drugs and leaving the scene of a serious injury accident.