Metro resumed rail service on three lines in part of downtown Washington on Monday after a brief suspension.

The transit agency said service was suspended between the McPherson Square and Smithsonian stations on the Orange, Silver and Blue lines because of fire department activity at Metro Center. Metro spokeswoman Sherri Ly said the agency is investigating a report of a possible arcing insulator.

Smoke at the station has since dissipated, she said. First responders determined it was a maintenance issue and have cleared the scene, Ly said.

The D.C. fire department tweeted, “We are clearing the scene and Metro is handling."

The service suspension lasted about 30 minutes before trains began single-tracking.

Arcing on a track happens when stray electrical current from the rail’s third rail finds another path to the ground, usually because of puddled water, mud or dirt.

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