HOPKINTON — Veteran Fire Chief Richard Schaefer died of heart attack Sunday night, after working a busy shift during the Hopkinton State Fair.

Schaefer was taken by ambulance from the fire station to Concord Hospital, where he suffered cardiac arrest, according to a statement from the Hopkinton Fire Department.

Schaefer joined the fire department in 1979. He was promoted to chief in 1999.

An autopsy has not yet been performed.

“His sudden death has left his fire family and friends in shock. We offer our sincerest condolences to the family,” the fire department said in its statement.