Police are investigating whether break-ins at two firehouses last week were related. Sag Harbor Fire Department Chief James Frazier reported a burglary at the headquarters on Brick Kiln Road in Sag Harbor Village on the afternoon of Sept. 23. Village police said someone broke into the change machines in the recreation room, taking an unknown amount of money, and also stole about $15 from a donation jar. The burglary occurred between 9 p.m. on Sept. 22 and 1 p.m. on Sept. 23, police said. In Bridgehampton, fire department officials reported a break-in at the firehouse on School Street last Thursday. Southampton Town Police Detective Sgt. Lisa Costa said someone got into the firehouse through the bathroom window in the basement, which is undergoing extensive interior renovations, sometime between Sept. 24 and last Thursday. “They rummaged through the fire trucks and used some tools to pry into the offices,” she said. Nothing was reported missing, but things were left “in disarray,” she said. Detective Costa said police are looking into whether the two burglaries are related.