WASHINGTON (AP) — Metro officials say one of the busiest stations in downtown Washington has been evacuated because of smoke.

Metro police say the L’Enfant Plaza station was evacuated shortly before 3:30 p.m. Monday. Metro says trains on the yellow and green lines aren’t going through the station at all, and blue, orange and silver line trains are going through the station but not stopping. Metro says no injuries have been reported.

Authorities say the source of the smoke is unknown. A District of Columbia fire department spokesman says firefighters are on the scene but did not immediately find a fire.