Three Injured After MBTA Train Evacuated in Boston

— -- Riders on a Massachusetts Bay Transportation Authority train in Boston were forced to climb out of train car windows this afternoon after smoke filled the air at Back Bay Station, resulting in three minor injuries, according to the MBTA.

At 4:39 p.m., the MBTA operations center learned of an issue with a train departing the Back Bay Station, resulting in visible smoke onboard the train, according to MBTA.

Three people were transported to a nearby hospital to be treated for injuries from the incident.

Videos from the scene show riders busting windows open, helping each other climb out of the train cars.

The MBTA says the doors on the train remained closed because the train had begun its departure from the platform, which does not constitute a malfunction. The motor person had begun promptly opening doors to allow passengers to evacuate safely, according to the transit agency.

By 4:57 p.m., the Boston Police Department evacuated the station. By 6:15 p.m. service was restored to Back Bay.

According to the MBTA, the cause has not yet been determined, but it is believed it related to the motor.

ABC News' Aaron Katersky contributed to this report.