All the commuter-rail lines in and out of South Station - save the Worcester and Kingston lines - are now reporting delays, possibly because a train slipped just a bit off the rails. Based on the delay times posted by the T, we're guessing it's the 1:17 p.m. outbound Fairmount Line train, which the T reports "remains stopped after South Station and is 45-55 minutes behind schedule."
Amtrak reports "lengthy delays" due to "a disabled commuter train blocking the tracks in the area."