Nicola and Lisa Henton-Mitchell were on holiday with their children, aged 12 and nine, in Italy when they were forced to abandon their car and take shelter in a tunnel.
A huge section of the Morandi Bridge collapsed, sending more than 30 cars and three trucks plunging to the ground as far as 150ft below, during a violent storm on Tuesday.
“The rain was torrential and as we drove along we felt the car slide to the right,” Lisa, who is from Bicester in Oxfordshire, told the BBC.
“We kept going, then all of a sudden we saw lots of red lights, all the cars in front braking. We could only see a couple of cars ahead of us.
“Then all of a sudden all of the reverse lights came on.”
Nicola said people started shouting and waving their arms out of car windows to tell people to reverse.
Lisa said: “We tried to reverse and we couldn’t go anywhere and the car in front hit the front of our car and people were running, screaming in Italian, ‘Run, out, everyone out, cars’.
“So we just literally (said), ‘Kids run, run’ because we didn’t know what was happening.”
She added: “We left everything in the car and we just ran for our lives because we didn’t know.”
Italian prosecutors are focusing their investigation on possible design flaws or inadequate maintenance, with fears rising that a part of the motorway bridge which is still standing could also come crashing down.
Authorities have widened their evacuation to include some 630 people living nearby, while around 1,000 rescue workers continued their search through tonnes of rubble for any more bodies.