Teen's legs severed by train at Taree

A teenager's legs have been severed after he was hit by a train on the NSW mid-north coast.

The 18-year-old had both his legs cut off when he was struck at a railway crossing in Taree.

Police believe he had earlier been celebrating his birthday at a nearby residence with family and friends.

Emergency services found the man on the tracks with his legs severed, at about 4.30am on Sunday.

He was taken to Newcastle's John Hunter Hospital in a serious condition.

The male train driver, from Queensland, stopped the train soon after the accident and contacted emergency services.

Bystanders caused havoc for emergency services at the scene.

While police investigated the scene, a group of people threw rocks at them and the 33-year-old train driver.

Officers were forced to take refuge in the train driver's cabin.

Ambulance paramedics were also blocked, pushed and verbally abused by the group during their initial attempts to treat the teen.

An ambulance vehicle was damaged after being hit by rocks.

Police called in reinforcements to disperse the group.

A crime scene has been established and investigations are continuing.

The train driver was taken to Manning Base Hospital for mandatory blood and urine testing.