A small track fire erupted underneath a Red Line train shortly before 6 p.m. at Park Street, forcing the evacuation of the train and a shutdown of Red Line service.

"Never a good sign when there's smoke pouring out of the T station you're entering," Anne Holmer tweeted at 5:54 p.m.

Over in Central Square, David Day reports "Tons of Noam Chomsky fans spilling out of Central Square Red Line looking for cabs." Chomsky was scheduled to speak at Occupy Boston this evening.