Horrified residents of St Asaph have described the deluge which wrecked their homes.
An elderly woman was found dead in one property and dozens of families were forced to flee after the River Elwy burst its banks.
Helen Ross, 37, a parent liaison co-ordinator at a local school, said the devastation was "heartbreaking", adding: "I have lived here nine years and I have never seen the river cause flooding like this. My husband phoned me at 7am to say parts of the city were being evacuated. I looked out of the window and there was water over the road and then, within an hour, it was in the house."
Mrs Ross, a mother of two, said the water level reached more than a foot above her floorboards. Extensive damage was caused to her living and dining rooms and kitchen. "We've lost everything downstairs," she said, wiping away tears. "It's heartbreaking."
At St Asaph Leisure Centre, which has been transformed into an evacuation centre, about 150 people had gathered for shelter. Wheelchair user Brian Shone, 74, told how he went for his morning newspaper at 7am and less than an hour later his terraced house was flooded.
He said: "I could see water rushing past as I went to the shop but I was on my mobility scooter and thought I was all right. My carer came about 8 o'clock and I looked out of the window and the water was creeping up the garden path. I turned around and there was water already inside from the back. It came into the house so quickly, we didn't have time to do anything about it."
Julia Edwards, a social worker tasked as manager of the evacuation centre, said: "There's about 150 people in the centre, all very wet and all evacuated from their homes. There are children in there, there are pets, there's a lot of noise but everyone seems to be OK."
She said the residents were trying to remain upbeat, adding: "We're making sure everybody has tea or coffee and the school has just served lunch to everybody. We've got slippers and blankets and it's just about making sure we're there to help people. Some people have just left their houses with nothing but the clothes they were wearing. Some left behind medication and lots are worried about their possessions. But we're helping as much as we can."
Dave Hallows, emergency response manager for the British Red Cross, said he had a team of 17 volunteers assisting the people of St Asaph. He said: "People seem to be coping quite well at the moment. But they know they can't go home until the waters have receded and obviously that causes them worry, particularly those who have no access to alternative accommodation."
Meic Davies, flood response manager for the Environment Agency Wales, said the city was overwhelmed because the river water rose over the flood defences. He said: "It's devastating what has befallen the residents here."