After a transit train took off without an operator during Thursday's morning commute near Boston, Gov. Charlie Baker says the train was "tampered with." The question now, Baker says, is whether this was "negligence versus something else."

About 50 passengers were aboard the Red Line train when it left the Braintree station south of Boston without an operator about 6 a.m. Thursday. The Massachusetts Bay Transportation Authority says power was cut to the train "within a couple of minutes," according to member station WBUR.

No injuries resulted from the incident, which set off "severe delays in both directions" of travel on the Red Line, the transit agency says.

Around midday, Baker said of the train, "it's pretty clear that it was set in forward motion, which is why it moved in the first place, when the signal was manipulated."

Fred Thys of WBUR reports:

"Gov. Baker says the power to the third rail was shut off within a couple of minutes. But the train coasted, because it had momentum at that point, forward through several stations before it came to a stop. Inspection of the train determined that some of the controls had been manipulated."Baker says the driver got out of the train to check on a signal problem when the train left the station on its own."The governor says it's pretty clear that the main control that drives the train was tampered with. He says the investigation is focusing on whether this was negligence or intentional."Copyright 2016 NPR. To see more, visit