Federal investigators are probing a crash on the Green Line last weekend in Somerville that sent four train operators and one passenger to the hospital.

The NFL said the person was part of the 400-member field cast and had hidden the flag on himself before the halftime show began Sunday night. Reports have surfaced explaining why Brittany Mahomes and Taylor Swift were not seated together in the same VIP box during the Super Bowl.

Max Desmond, 31, was one of the passengers on the Green Line train that collided with another parked train at the MBTA East Somerville Station just after midnight on Sunday.

A federal investigation is now being launched into the crash on the Green Line that left someone hurt and snarled travel for thousands in Boston on Monday.

Five people were taken to a hospital early Sunday morning after an MBTA Green Line train with passengers hit a stationary train at a station, according to the MBTA.