Rancho Santa Fe

A 3-year-old boy was killed when the car his 18-year-old baby-sitter was driving crashed into a bus, authorities said.

Michaela C. Shannon was driving about 45 m.p.h. on Via de la Valle, near Cancha de Golf about 6:30 p.m. Sunday when she was “distracted by something that the child was doing,” California Highway Patrol Officer Steve Ussher said.

Shannon bent to pick up something from the car floor for 3-year-old Weston Marchelli, then looked up and saw a parked bus directly in front of her, Ussher said. She had no time to hit the brakes and crashed into the rear of the bus.

Weston, who was in the front seat, was wearing a lap belt but no shoulder harness, Ussher said. According to state law, any child under 4 years old or weighing less than 40 pounds must be in a car seat.

The child died of internal injuries from the seat belt and was injured by the door and dashboard, which were pushed into the right front seat, Ussher said. He died at Sharp Memorial Hospital at 10:34 p.m., officials said.

Shannon and Weston’s 6-year-old brother, Grant, who was in the back seat, received minor injuries. Both are from Cardiff, Ussher said.

The driver of the bus and its eight passengers were not injured.

Ussher said officials may recommend filing charges against Shannon.