An eight-year-old girl is in a critical condition in hospital after a nine-year-old classmate shot her during a lesson.

The girl was taken by air ambulance from the Armin Jahr Elementary school in Washington State to Harborview Medical Centre in Seattle.

A district school spokesperson, Patty Glaser, told journalists that the police were still investigating the incident which happened on Wednesday afternoon.

"It's very early in the investigation. As a parent I can only imagine. Our prayers go out to the families," Ms Glaser said.

She added: "We do know the gun and the student were found"

Police are treating the shooting as an accident and there are currently no reports about how or why this happened.

District authorities said grief counsellors would be on hand for students, staff and parents.

The school told parents to come forward if they had any information: "We want to assure you that incidence [sic] such as this are rare in our community and we want your child to always feel safe."