Residents in riverside properties in Ironbridge have been told to leave their homes and businesses immediately after temporary flood barriers were overwhelmed by water.
The barriers holding back the floodwater from the River Severn moved overnight in Shropshire and police said they appeared to be buckling under the pressure.
Flooding along parts of the river, which remained close to its highest levels in some areas, is likely until at least Sunday, the Environment Agency said.
West Mercia Police Chief Superintendent Tom Harding said officers were visiting residents of Wharfage to tell them to evacuate.
He said in a video on Twitter: "Potentially, we've got water that has started to come underneath the flood barriers and in areas it appears that it is buckling.
"We want to be open and transparent with the public and residents here so they make that informed decision to come with us."
Police could be seen knocking on doors along the riverside to ensure that residents living on Wharfage had left their homes.
Barriers were also erected in side streets to ensure that people did not approach the river.
Temporary flood defences along Wharfage had been pushed back towards a pub and other businesses, sparking fears that the defences could be fully breached.
Some residents declined to leave their properties, including one occupant who also opted not to move a car parked within yards of the riverside.