Mystic —The recently renovated Mystic drawbridge was unable to fully close for about three and a half hours Sunday evening, preventing cars from crossing the Mystic River in the downtown area.

The problem, which Connecticut Department of Transportation workers said was an electrical issue, was reported at 5:10 p.m. Pedestrian traffic was occasionally disrupted while DOT employees raised and lowered the bridge as they tried to resolve the issue. For most of the evening, however, pedestrians were allowed to cross the bridge “at their own risk,” said Groton Town police officers. Because the bridge was not fully closed and locked, cars were not allowed to pass. The span reopened about 8:30 p.m.

Stonington police detoured traffic down Holmes Street to Route 27 and out to Interstate 95, which was already congested at Exit 90 with holiday weekend traffic.

This is the second malfunction of the drawbridge within a month. On June 10, the drawbridge was closed for 90 minutes following an afternoon malfunction that temporarily backed up traffic and forced detours in Groton and Stonington. The state completed a $14.8 million rehabilitation of the bridge this spring.