More than 450 MBTA passengers were evacuated from a Blue Line train in the tunnel under the Boston Harbor due to a signal issue Tuesday afternoon.

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

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