An ambulance has caught fire and exploded at St Helier Hospital in Sutton.

A large area around the hospital has been cordoned off as firefighters tackle the blaze amid fears that superheated gas cylinders could explode.

Police have confirmed sections of the hospital near the fire have been evacuated.

Reports from the scene suggest parts of the maternity and pathology sections have caught fire.

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Residents said they heard a big explosion followed by plumes of black smoke from near the pathology and women's health/maternity area of the hospital.

Michelle Johnston, 37, said her children heard the blast as they played in the garden.

Mrs Johnston said: “You can’t get anywhere near there.

"There’s too much smoke and too many people around, so they’re not letting anyone get near it. The roads are closed.

“Some people are telling me that it was an ambulance that exploded.

“A doctor I know said that apparently an ambulance caught fire and the oxygen tank exploded.

"I don’t know if there’s anyone hurt at the moment, but I’m walking up there to see what’s going on.

Mrs Johnston said: “I saw a bunch of nurses parking their cars on the green nearby and running down to the hospital.”

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A hospital worker, who did not want to be identified, said: “I saw the burnt ambulance and it was just a shell. It doesn’t look like an ambulance any more.”

A man who did not want to be identified said: “My son was at the other side of the green when it happened. He heard the noise and saw the smoke, but he didn’t see the explosion.”

It is not clear what caused the fire.

About 80 hospital patients and staff were evacuated from the immediate area.

A spokesman for the London Fire Brigade said: “We know there was one ambulance that was quite badly damaged and there was a second ambulance that suffered a bit of damage as well.

“Crews are still at the scene and will be down there for a little while. As far as I’m aware the fire was put out."

London ambulance said "Our control room was told at 5.02pm that one of our vehicles had caught fire outside St Helier Hospital.

"We have two ambulance crews, two duty officers and a manager on standby on the scene.

"My staff have treated one patient, a firefighter for minor injuries."

A paramedic from another unit, who did not want to be identified, said: “There was a Battersea crew down at St Helier and they were trying to get our control’s attention to the fire by pressing the priority button.

"It turns out the control was taking another priority call and before they could respond I heard a boom on the radio.”

A spokesman for Epsom and St Helier University Hospitals NHS Trust said an ambulance caught fire outside the hospital.

"There were no serious injuries or fatalities but London Ambulance say they treated one firefighter.

"We are not sure yet what caused the explosion.

"I don't know the answer to whether any of the hospital buildings have been damaged.

"The police will not let us down there yet."

The B278 Wrythe Lane has been closed both ways due to the fire near Tweeddale Road and Thornton Road. Bus routes 151, 157, S1 and S4 have been diverted and motorists in the area are reporting heavy congestion.

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