UPDATE, 2:36 p.m.: The MBTA reports the station and tracks are back in service and Green Line service has resumed with, of course, residual delays.
Emergency responders raced to Boylston station, where one outbound trolley rear-ended another around 11:50 a.m. Matthew Gamber , who was in the first car of the train that got hit, tweeted at 11:54:
B Line outbound at Boylston just came to screeching stop, tossing unsuspecting passengers. Not leaving station soon.
The department says nobody was entrapped and that neither trolley derailed.
John Keith , on scene, reports EMTs set up a triage area on Boston Common. One passenger told him, "it felt like a bomb went off."
Traffic around the area quickly ground to a halt as ambulances raced to the scene and set up on Tremont Street to await the injured.
This is the first Green Line collision to result in injuries since Oct. 8, when two E trolleys became entangled . Scott Page tweets  that the hitting trolley car, 3679, was last in a collision in 2004.