Live wires that somehow fell from the Gilmore bridge set debris and old railroad ties on fire, causing thick black smoke visible for miles around and shutting down commuter-rail service into and out of North Station.
The fire broke out around 11:40 a.m. on the Cambridge side, bringing fire crews from both Cambridge and Boston and eventually setting fire to the underside of the bridge itself.
Jack Suslak tweeted from a train heading toward North Station around noon:
We are backing up our train to porter square to connect to red line not allowing any trains into Boston.
The fire was knocked down around 12:20 p.m., according to the Boston Fire Department, which says firefighters had to go through a decontamination process at a station set up at Boston Sand and Gravel, due to the unknown nature of some of the stuff that was burning.