WESTPORT—Customers at Stop and Shop had to take an unexpected shopping break on Friday morning when a fire alarm went off at the store.

The Fire Department responded to an alarm at the Stop and Shop at 1790 Post Road East just before 10 a.m., Assistant Fire Chief Kenneth Lombardi confirmed.

Firefighters determined a heating, ventilation and air conditioning unit on the roof was causing smoke to enter the second floor of the building. They shut the unit down and reopened the store. Lombardi said that smoke that had entered the building was confined to a second-floor office area.

No one was injured at the Stop and Shop and the Fire Department left the scene about an hour after the call. The Fairfield Fire Department assisted Westport at the scene while the Norwalk Fire Department covered at Westport’s headquarters while their firefighters were on the call, Lombardi said.

Lweiss@hearstmediact.com; @LauraEWeiss16