A Spanish train that hurtled off the rails and smashed into a security wall as it rounded a bend was going so fast that carriages tumbled off the tracks like dominos, according to eyewitnesses and video footage.

Spanish investigators were today trying to find out why a passenger train jumped the tracks and sent eight cars crashing into each other killing at least 77 people and injuring more than 140.

Spanish prime minister Mariano Rajoy is heading to the scene of the crash in north-western Spain that killed 77 people in one of the country’s worst rail accidents in decades.