A Green Line train derailed outside Park Street station just before midnight on Monday, MBTA officials confirmed on Wednesday.
The two-car train was slowly moving through a track switch when one of the cars derailed, according to MBTA spokesman Joe Pesaturo. Two passengers were on the train, and no injuries were reported he said.
MBTA personnel re-railed the car, cleared it from the mainline, and made repairs to the track overnight, Pesaturo said.
Green Line service operated as scheduled on Tuesday morning, he added.
The incident was not noted on the MBTA’s Twitter account, which usually reports delays and derailments.
The Federal Transit Administration, National Transportation Safety Board and state Department of Public Utilities were notified of the incident, Pesaturo said.
The cause of the derailment is under investigation, he said.