An MBTA spokesperson said the train operator stopped the train after they spotted a downed wire in the tunnel.

Hundreds of passengers aboard the Blue Line were evacuated Tuesday afternoon after a train became stuck beneath the Boston Harbor, between the Maverick and Aquarium stations, officials said.  Over the course of about an hour,

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