Emergency crews performed lifesaving measures on the boy when they arrived on scene. No other children were on the bus at the time.

FAIRFAX COUNTY, Va. - Police are investigating the death of a young boy who experienced a medical emergency on a Fairfax County school bus Thursday.

The incident happened in the 2300 block of Dulles Station Blvd. When emergency crews arrived on the scene, they performed lifesaving measures on the boy. He was later pronounced dead at a hospital.

A Fairfax County Public Schools bus emblazoned with handicapped stickers was parked in the Dulles Station apartment community Thursday evening, puzzling neighbors.

"It was totally shocking," said Valerie Roseborough, who saw police and ambulances parked outside her design studio. Police say they were dispatched to the scene at 1:57 p.m. Thursday.

Police say there were no other children on the bus.

"It's just struck me as odd," said Roseborough, whose son goes to a Fairfax County high school.

The county's major crimes bureau is investigating as a formality, said police spokesman Lt. Eli Cory, adding that police think the death was not criminal.

Fairfax County schools released a statement calling the death "tragic." Spokesman John Torre said the school system is cooperating with police.

Police are not able to say which school the child attended or his age, citing recently enacted state privacy laws.

No other children were on the bus at the time.

Officials continue to investigate.