A deer was struck by a train before being electrocuted and bursting into flames - leaving passengers fearing they were in a terrorist attack.

The animal was struck at the exit of the Balcombe Tunnel at around 7am yesterday.

The deer was then electrocuted by the live rail and caught fire as the train arrived at Gatwick Airport station.

Frightened passengers told how they fled the train in panic after hearing a loud bang before their carriage filled with smoke.

The incident, involving the 6.40am First Capital Connect Service from Brighton to London, caused delays to services until after 4pm yesterday.

Passenger John Ellis, 57, from Dubai, was travelling on the train to Gatwick on a business trip.He said: “There was a loud bang from under the front carriage where I was sitting.

“Sparks and fire then appeared outside the train and the carriage started to fill with smoke.

“All the electrics failed and there was panic as people screamed, shouting at each other to get out and fighting the smoke and darkness to evacuate the train.

“People tripped and fell during the panic. The platform was heaving with people.

“Most assumed it was a bomb explosion or terrorist attack.

“I could see the remains of the deer under the train as I escaped.”

Eyewitnesses also said passengers fled the train without their luggage and had to later pick up their belongings from a collection point.

Another commuter described waiting more than four hours to get to London from Hassocks because of the delays.

He said: “Many folk missed flights while others were visiting family but had to cancel their trips.

“There were delays, cancellations and confusion.

“I waited ages at Haywards Heath on the train, was slow to move to Three Bridges and then everything completely stopped.

“There was supposed to be a replacement bus to Redhill but that had a queue of 200 people and no bus arrived.”

A spokesman from Crawley Fire Station said crew were called to the incident at just before 7am.

Network Rail, which helped remove the animal, said it wouldn't usually expect a deer to “cause such damage.”

A Network Rail spokesman said: “Unfortunately in this case there were also engineering works on the line which were at a stage where they couldn't be lifted which made working around the incident more difficult.”

A spokesman from First Capital Connect said: “The animal's torso came in contact with the third rail as it arrived at Gatwick Airport, causing a small controllable fire which was soon dealt with by emergency services.

“Southbound services ran with 90 minute delays and bus replacement services were in operation.”