Mystic - The Mystic drawbridge on Route 1 is back open following a malfunction that temporarily backed up traffic and forced detours in Groton and Stonington for about an hour and a half late this afternoon.

Police said they started taking down detour signs shortly before 7 p.m. The bridge was first reported closed at about 5:30 p.m. The source of the problem with the recently renovated bridge is unknown.