At least 51 people have been killed in flash floods sweeping the eastern Spanish region of Valencia after torrential rain on Tuesday left roads and towns under water, local authorities said on Wednesday.Rescuers using dinghies worked in the dark to scour the floodwaters, rescuing several people, television pictures from the town of Utiel showed, and on Wednesday emergency services were working to reach the worst-hit areas.Carlos Mazon, regional leader of Valencia, said some people remained isolated in inaccessible locations.“If (emergency services) have not arrived, it’s not due to…