Groton — City police on Tuesday said they arrested three juveniles last week on charges they intentionally set a fire that damaged an unoccupied Thames Street home.

The three males, ranging in age from 15 to 17, were charged with third-degree arson, third-degree burglary, second-degree criminal trespass and first-degree criminal mischief. Their names were not released because they are under the age of 18.

Police, working with the city and state fire marshal’s offices, investigated the Sept. 20 fire at 426 Thames St., according to a statement from City Police Detective Sgt. Jad C. Bickford.

Police said the youths set fire to some furniture items in the basement of the home, causing more than $1,500 worth of damage. They also were involved in starting a small grass fire in the area, police said.

The three were referred to the Juvenile Matters division of Superior Court.