WASHINGTON — It was one of the scariest events for Metro riders in recent history: Smoke filled a train at L’Enfant Plaza in January 2015, killing a woman and sending 91 people to the hospital.

On Tuesday morning, the National Transportation Safety Board will look into what caused the emergency situation.

Metro riders gasped for air, doubled over and became sick in the street the afternoon of Jan. 12, 2015.

[related_gallery align=”right”]The event stands out in the minds of the roughly 400 on board, and for those caught in the ripple effect of the Yellow Line emergency.

“I probably shouldn’t say this, but I think it’s great the U.S. Department of Transportation is keeping the heat on WMATA and the local jurisdictions to move faster to turning around WMATA,” said D.C. Council chairman Phil Mendelson.

As the NTSB takes up the event at its board meeting, Mendelson hopes WMATA’s federally mandated safety changes are kept under the microscope.

“It’s clear there’s a lot of deferred maintenance to catch up on and safety needs to be a higher priority,” he said.

The federal board is expected to determine a cause of the smoke event and make recommendations going forward.

The NTSB released its initial findings shortly after the event, indicating that power was not cut to the energized third rail for 45 minutes as an electrical problem released heavy smoke into a Metro train.