BOSTON (WHDH) - An investigation is underway into what caused a Green Line train to derail in Boston on Saturday, officials said.

A westbound Green Line B Branch trolley derailed just west of the platform at Kenmore Station around 9 a.m. and there were no injuries, according to the MBTA. The estimated 25 passengers on board at the time were safely evacuated and escorted back to the platform.

The T is now replacing B Branch service with bus shuttles between Babcock Street and Copley C and D Branch riders are being asked to board shuttle buses at Copley for service to points west, while inbound service on these branches will end at Kenmore, with shuttle buses available.

In a statement, MBTA General Manager Phillip Eng said, in part, “We understand the frustration this incident causes for riders, particularly those who have been awaiting the return of service during construction. We want to assure passengers that we are diligently working to restore regularly scheduled service as soon as possible and investigating the cause.”

The statement continued, “Safety remains our top priority. This incident underscores the importance of our ongoing efforts to enhance the reliability and resilience of the MBTA system following decades of underinvestment. We are committed to identifying the root cause, implementing necessary corrective actions, and keeping the public informed every step of the way.”

Also Saturday, a downed Amtrack power line caused service disruptions on the Orange Line and Commuter Rail. That issue has since been resolved.

This is a developing news story; stay with 7NEWS on-air and online for the latest details.

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