Officers are appealing for information after abandoned farm buildings at Cow Dyke Farm, in Skipton Road, were deliberately set on fire at around 7.15pm on Sunday, June 20.
A North Yorkshire Police spokesman said: "We are appealing for witnesses and information about an arson that occurred at Cow Dyke Farm.
"A group of teenagers are suspected of setting fire to abandoned farm buildings.
"We are requesting the public’s assistance to help establish the full circumstances surrounding the incident.
"In particular, we are appealing for information about any identification of people who were in that area at the time.
"Anyone with information that could assist the investigation should contact North Yorkshire Police on 101, quoting reference number 12210143681.
"If you wish to remain anonymous, you can pass information to Crimestoppers on 0800 555 111."