Motorists risked their lives weaving through a closed railway level crossing after a storm blew out power on the line.
Barriers across the A27 between Lewes and Eastbourne stayed down after a thunder and lightening storm knocked out power on the line at Beddingham.
Impatient drivers ignored the danger and zig-zagged their way between the gates.
Police, Railtrack and motoring organisations said drivers took a huge and foolish risk.
A spokeswoman for Sussex Police said: "At a time when everyone is trying to reduce the number of accidents, this was sheer stupidity."
Railtrack condemned drivers as crazy.
Andrew Howard, head of road safety at the AA, said: "These drivers were foolish. The consequences of a train and vehicle collision are huge."
Mike Legg, a sports writer, was one of the motorists caught at the crossing.
He said: "The barriers came down as normal but no trains came through. After five or ten minutes people started to get impatient.
"One guy got on his phone and was talking to some of the other drivers. Then they got back in their cars and a few pulled out and drove up to the barriers, hesitated and then weaved through the middle.
"About five or six cars went through from the Eastbourne to the Lewes side, a couple came the other way and a couple of motorcycles went through. I thought it was a dangerous thing to do and not to be recommended.
"It was raining hard and no one knew for sure when the next train was coming. Two trains did come through after that although they were going very slowly."
Drivers were only stopped from driving through the barrier when a motorist parked his car across the road on the Eastbourne side to block the way through the barriers.
Sussex Police said an off-duty officer was caught in the tail-back and quickly took charge to stop other drivers breaking through the barriers.
Jane Vincent, spokeswoman for Railtrack, said the flash storms caused several problems with power supplies.
She said: "The power at Beddingham failed at 9.22am and was restored at 9.46am. There were still problems after that so the crossing is being operated manually until everything is safe and tested.
"If the barriers are down it is very foolish to try to drive round them. They should have waited or found a different route."
Mr Howard said: "The Highway Code says you must not zig zag around the barriers."
However, he admitted there was no written guidance in the event of a total power failure at a barrier crossing.
He said he would bring the matter up at tomorrow's Railway Safety conference, Operation Lifesaver.
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