Orange Line train fire sends passengers scrambling along bridge in Somerville

Passengers scrambled out of train windows and scurried along a rail bridge Thursday after an Orange Line train approaching Assembly Station caught fire as it crossed the Mystic River.

Approximately 200 passengers clambered off the southbound train, after flames and smoke were seen from the head car at approximately 6:45 a.m., according to a statement from the MBTA. One passenger exited the train and jumped into the water before being retrieved by public safety personnel. There were no known injures, according to the T.

“Obviously, this is a frightening incident, and not the type of service that we want to provide to our customers. I want to offer my apology to the folks that were on that train,” said MBTA General Manager Steve Poftak during a press conference Thursday afternoon.

Poftak said the T's initial findings indicate the fire ignited after a 6-foot-long piece of metal siding, called a sill, came loose on the underside of the train, made contact with the third rail that carries electricity, and sent sparks flying.

The 42-year-old train, which was last inspected on June 23, has been pulled from service, Poftak said. He did not know whether the metal sill was an original piece of equipment or how fast the train was moving when the fire started.

Poftak said investigators were still looking into the cause of the fire, and he did not know whether the ongoing heat wave played any role. He said T management will review its evacuation protocols.

The power was turned off within two minutes of the start of the fire, Poftak said, and the train was brought to a railyard for inspection. He said the T also examined the metal sills of all other Orange Line trains in service and discovered no issues.

MBTA spokesperson Joe Pesaturo told The Associated Press the train that caught fire was not one of several new Orange Line cars that were temporarily pulled from service recently when one car experienced a failure in its battery compartment. They have since been returned to service.

Shuttle buses that replaced train service between Oak Grove and Community College stations throughout the morning commute. By 10:40 a.m., rail service resumed with delays, according to the MBTA.

The MBTA has notified the Federal Transit Administration and the National Transportation Safety Board.

The FTA launched a review of Boston’s subway system in April following several accidents that led to injuries or death within the past year. The federal agency last month issued a series of directives to immediately address “longstanding issues” with the system’s “overall safety program and safety culture.”

“It’s extraordinarily frustrating when these types of incidents happen, but I think we have to take responsibility,” said Poftak. He said the MBTA and its partners are working hard to make the transit system safer.

With reporting from WBUR's Laura Kraegel and Aimee Moon, as well as The Associated Press