Somebody has turned off vital river defence flood pumps in Malton and Norton overnight.
North Yorkshire Councillor Keane Duncan says the police are now involved.
Church Street and St Nicholas Street residents and businesses woke up to water and raw sewage starting to flood roads getting very close to properties this morning.
Councillor Duncan said: “What we’ve seen overnight is reckless, selfish action that has created unnecessary panic and anguish in our community.
“It is only because of the swift action of the council, turning the pumps back on this morning that serious damage to homes and properties was averted.
“But this could have been so devastating here in Morton and Norton.
“We’ve alerted North Yorkshire Police, they’re stepping up patrols and reviewing CCTV to identify who is responsible and also locking down the pumps to make sure that further tampering cannot take place.”