BOSTON -- Boston police said at least three manhole fires in the city's theater district prompted the closure of several Back Bay streets early Monday and forced the Registry of Motor Vehicles to shut down all branch offices and online services because of the resulting power failure in its Transportation Building headquarters.

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NSTAR confirmed that the fires occurred in manholes near the intersections of Stuart, Tremont, Boylston and Washington streets, not far from the Boston Common.

Power was restored just before 11 a.m. after being out for about five hours.

No one was reported injured in the blasts, which occurred about 5:45 a.m., but traffic was affected and the MBTA said both the Copley outbound T station and the Arlington Street station were closed. They were reopened by 8:30 a.m., T officials said.

Power was also out in the surrounding area, meaning there was no electricity for traffic lights and there were outages in the nearby Radisson Hotel and the state Transportation Building. Workers there were told not to report to work until noon.

Students at the New England School of Law were also advised that there would be no morning and day classes at the school. Day classes were also canceled at Bay State College and Fisher College. The Quincy Elementary School and the Quincy Upper School were also closed, giving 1,200 students a day off.

The Snowden International School at Copley was also affected by outages, but classes were scheduled to take place, some of them in the Boston Public Library, according to Boston school officials.

Officials said it appeared some kind of cable malfunction was to blame for the blasts and one worker at the scene said he saw a flame shoot up at least 7 feet in the air when the fires erupted.

The intersection near the Transportation Building is normally heavily-traveled and motorists were advised to seek alternate routes.

NewsCenter 5 and the Boston Channel.com will have more details as they become available. Refresh this page for updates.