The 50- to 60-year-old steel cable probably “weakened until the point where it came down” after decades in a damp, subterranean tunnel, said Phillip Eng, the MBTA general manager.

It took firefighters approx. 1 hr to evacuate 500 people from a ⁦ @MBTA ⁩ Blue Line train that was disabled under the harbor between Maverick & Aquarium station. They used the Nolan cart to transport anyone needing assistance using 3 exits , 2 in Boston & 1 in East Boston pic.twitter.com/8fYoSYLJHJ

Around 500 MBTA riders were reportedly stuck on a Blue Line train Tuesday afternoon, according to officials. The train was disabled under the Boston Harbor between Maverick and Aquarium stations, the Boston Fire Department reported. It took firefighters about an hour to evacuate the 500 people through the tunnel.