What’s more Boston than T delays on Marathon Monday?

As marathoners from around the world finished in Copley Square Monday afternoon, the MBTA terminated Green Line service at Arlington, leading to delays on one of the city’s busiest days of the year.

Exhausted and drenched runners who just finished the grueling 26.2 miles were stranded on trains and platforms. Some marathon spectators along the route had held signs that read, “You’re faster than the T,” which was especially true on Monday.

“Probably should have just kept running back to Somerville. #mbta,” a marathon finisher tweeted as he waited for a Green Line train with throngs of people at Prudential station.

The MBTA said a “mechanical failure” was to blame.

At about 2:50 p.m., an eastbound Green Line train became disabled at Boylston Station. While crews worked to get the disabled train moving, Green Line service was suspended between Arlington and Haymarket stations.

Then the MBTA set up a bus shuttle between Arlington Street and Back Bay stations, and riders were asked to use Orange Line service between Back Bay and Haymarket/North stations, which also have Green Line platforms.

“The disabled train was on the move again at approximately 3:50 p.m. and Green Line service resumed,” an MBTA spokesperson said in a statement.

“While service was suspended, some trains were held in between stations until MBTA personnel made arrangements to safely move the trains back into station platforms where passengers exited,” the spokesperson added. “The MBTA apologizes for the disruption in service.”

Transit Ambassadors and MBTA personnel helped customers at stations and service announcements were made on trains and in stations.

The cause of the mechanical failure is under investigation.

Phillip Eng took over as the MBTA’s general manager last Monday.