A firefighter in a hazmat suit was called in after a large amount of foam started bubbling up from a North Yorkshire street.
It emerged without warning in the Denison Road area of Selby this morning.
Residents called in the North Yorkshire Fire & Rescue Service.
Station Manager Tony Walker said on Twitter: “A crew from Selby and a hazmat officer have responded to a call in the Abbots area of the town.
“Reports of foam coming up from the drains had some residents naturally concerned.
“The substance was tested and deemed to be none toxic though the cause is not known.”
Firefighters then washed away the foam.