ARSONISTS set light to a privately-owned paramedic ambulance based at Sittingbourne's Bayford Meadows kart circuit last night. Inside were four oxygen cylinders, one of which exploded in the intense heat.

Shards of metal debris were flung 50 yards onto the circuit and the noise of the explosion could be heard miles away (Stuart Somers writes).

The ambulance was destroyed and the explosion also pushed in the walls of the circuit's smart American diner themed restaurant, causing toilet cisterns to be wrenched off the walls and spraying water everywhere.

All the windows of a nearby briefing room were smashed, as were windows on the track sweeping truck and a caravan belonging to the Sittingbourne Christmas Lights Committee. Total damaged is estimated at about £50,000.

Sub officer Mark Innes from Sittingbourne fire station said: "If we had arrived at the scene a few minutes earlier then firefighters could easily have been killed.

"All we knew when we approached the fire was that it was some form of vehicle. We did not know it was an ambulance with oxygen cylinders inside.

"We had to drag three more cylinders out of the vehicle but this was safer to do so because the heat subsided once the ambulance blew apart."

Track owner Gerry Lilley said: "Whoever did this is the scum of the earth and they only did this to fuel their ego and pleasure.

"I hope they feel very guilty because the fully equipped ambulance was used to deal with emergencies on this very popular circuit. It will not stop our operations because we will sort out other emergency cover."

The arsonists had cut through the ambulance's locks and moved it forward before setting light to it.

Police spokesman Sally Farrell said: "We are definitely treating it as an arson attack. We are keen to trace the occupants of two vehicles seen in the area at the time of the incident. One was a silver Ford Mondeo and the other was another Ford which had two stripes down the side.

"The driver of the Mondeo is described as having a large build and the driver of the other Ford is believed to be male. His passenger was female with curly hair and glasses."

Anyone with information is asked to ring Crimestoppers on 0800 555 111.