The Green Line experienced major delays today after a trolley derailed in the tunnel between the Blandford Street and Kenmore stations, officials said.
No injuries were reported in the incident, said MBTA Transit Police Lieutenant Manes Cadet.
By the late afternoon, regular service on the C and D branches had resumed, according to the MBTA website.
But shuttle buses continued to replace B Line service between the Kenmore and Copley Square stations in both directions, according to the website.
Normal Green Line service is expected to resume by early Tuesday, said MBTA Transit Police Lieutenant Daniel Fitzgerald.
MBTA officials are still investigating what exactly caused the derailment, Fitzgerald said.