Parts of West Yorkshire have been hit by flash flooding following a sudden downpour that lasted about 90 minutes.
The canal at Hebden Bridge breached its banks, flooding the town centre, West Yorkshire Police said.
The A646 in Mytholmroyd and B6138 New Road in Mytholmroyd remain closed.
Nearly a month's worth of rain, more than 40mm, fell in Hebden Bridge and Mytholmroyd in three hours, BBC climate correspondent Paul Hudson said.
West Yorkshire Police said a number of residents had reported losing electricity in the Mytholmroyd area.
Hebden Bridge resident Geoff Tansey said the rain was "really intense, like a monsoon".
Water levels were dropping in the town as the standing water was pumped away.
The Police said on Twitter that the Highways Agency had "removed 25 wagon loads of rubble", estimated to be about 500 tonnes, from roads in Hebden Bridge, in the clear-up operation.
The town's library was evacuated but Calderdale Council said waters should quickly subside.
West Yorkshire Police were directing traffic in Todmorden, Hebden Bridge and Mytholmroyd and motorists were advised to avoid the area.
The weather also caused severe disruption on bus and train routes.
Robin Ward, station commander at Todmorden fire station, said: "This is water that has come off the hillside.
"All the hillsides around the Calder Valley are saturated with water with nowhere for any rainfall to go.
"It's just rushing off and it's filled the canal and broken some of the becks and we've got water flowing into the town centre."
Jo Brock, who runs a nursery in Cragg Vale near Mytholmroyd, said: "The weather has been relentless and rain is coming down in torrents.
"It's very scary for a lot of people."
She said that the nursery, called the Ark, had not been flooded and would stay open until all the children had been collected by parents.
More than 500 homes and businesses in Hebden Bridge, Todmorden and Mytholmroyd were flooded in June.
On Friday Prince Charles visited areas affected by water damage, on a day that also saw heavy rain and flash flooding hit parts of the county.