After Massachusetts Bay Transportation Authority (MBTA) crews cut the power, the train coasted through four stations before it came to a complete stop, according the local CBS affiliate and other reports. The train travelled 9 minutes on its own, according to WBUR radio.

No passengers were hurt, but the train did brush by a conductor—perhaps its own operator—during its journey. The extent of his injuries, if any, is not known.

Massachusetts Governor Charlie Baker told reporters that it appeared that the controls had been manipulated and that the Department of Transportation and the MBTA are investigating the incident. The FBI was not involved, to his knowledge.

There is also the possibility of operator error and that theory appeared to be gaining steam later in the day.

It was unclear how fast the train travelled during its ghost ride, which started at Braintree Station heading to Boston and ended in North Quincy.

This is just the sort of bad news that Boston’s beleaguered MBTA, known as “the T,” doesn’t need after a number of weather-related snafus last winter.

But more broadly speaking, it raises concerns that trains, like cars, can be hacked and controlled remotely. Baker did not use the “H” word, instead saying it appeared that the train controls had been tampered with or manipulated. But the possibility of hacking is an obvious concern.

Cynical Boston commuters might question whether the T cars are modern enough to be hacked.

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This story was updated at 5:50 p.m. EST to note that the ride lasted 9 minutes and that authorities are starting to focus on operator error.