PORTLAND, Maine — Part of the city was without electricity Wednesday afternoon after a tractor-trailer struck a telephone pole near the corner of Preble and Oxford streets, knocking down power lines.

The power outage affected parts of Bayside and the downtown, roughly between Cumberland Avenue and Marginal Way to the north and south and Elm Street and Forest Avenue to the east and west.

The city said around 1:30 p.m. that traffic signals were out at several intersections in the area and that it might take five to six hours to restore power.

The affected area includes several social and city service facilities including the Preble Street Resource Center, the central office of the Portland Public Schools and Portland’s social services offices, which the city said would be closed Wednesday afternoon.

The Oxford Street Shelter still had power Wednesday afternoon, according to a city spokeswoman.