The father of a teenage man, who had both his legs severed when he was struck by a train, allegedly attacked the ambulance vehicle after they arrived to save his son.

Emergency services were called to Bushland Drive railway crossing in Taree on the NSW mid-north coast to find the 18-year-old on the tracks with his legs severed at about 4.30am on Sunday.

But police officers and paramedics who arrived, were forced to take refuge in the train driver's cabin, along with the 33-year-old train driver, after they were hurled with rocks by a group of people.

Paramedics were also blocked, pushed and verbally abused by the group during their initial attempts to treat the teen, and an ambulance vehicle was damaged from the rocks.

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An 18-year-old has had both his legs cut off when he was struck at a railway crossing in Taree on the NSW mid-north coast

Taree Inspector Allan Fidock told Daily Telegraph the father of the victim 'smashed the windscreen of the ambulance'.

'Today the father has been better to us and is apologetic for his actions,' he said.

'We are trying to find people and get an ID on a couple who threw rocks and smashed windows.

'It is horrific to have to deal with that and then deal with alcohol-induced friends and family. And they are having a go at the cops and ambulance officers.

'Initially we had two officers out there. We had to close the station down then because we had five people (at the scene).

'Then there was three or more police who rushed out there when they started in the morning. All up there would have been a maximum of eight police.'

Emergency services were called to Bushland Drive railway crossing in Taree on the NSW mid-north coast

The 18-year-old, who was celebrating his birthday with family and friends, was taken to Newcastle's John Hunter Hospital in a serious condition.

The train driver, from Queensland, who managed to stop the train soon after the accident and contact emergency services, was taken to Manning Base Hospital for mandatory blood and urine testing.

A crime scene was established and specialist officers attended the location and an investigation is currently underway into the circumstances surrounding the incident.

Police will also examine the actions of the group of people who threw rocks.

Police reinforcements were called and a number of other officers attended the location and dispersed the group. No one was injured as a result.

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