Channel 5 is reporting that Boston Police are treating Boylston Street as a crime scene.
NBC reported that President Obama has been notified about the explosion.
An unrelated electrical fire at the JFK Library in Dorchester has closed the library for the rest of the day.
Marathon officials and police are sending buses out to pick up runners who still are on the course. Those closer in are being redirected to the Common.
academicdave: Boston marathon run tracker still working, if you know a runner you can search here: baa.org/individual.html
The Federal Aviation Administration has issued a temporary flight restriction over Copley Square, an agency spokeswoman said. This reserves airspace for rescue and recovery efforts in a three-mile radius around the square at an altitude of 3,000 feet and below. The restriction won’t affect most aircraft, which don’t fly that low over the city, the FAA said, but will impact news helicopters. The FAA issues temporary flight restrictions frequently in the event of wildfires, chemical explosions, security for the president, and other events. - Chris Reidy, Globe Staff
MGH is treating 19 patients, six critical and five serious, reports WBZ.