Updated at 6:00 a.m.

Metro said Tuesday what riders thought was smoke at the Pentagon City stop is “haze” due to dust from recent work being done in that area on the rail line.

The station had just reopened after recent repair work under Metro’s SafeTrack program. The next round — #5 of Metro’s major rebuilding program starts Wednesday on the Orange and Silver lines.

But on Tuesday morning, many riders were worried that it was smoke and dangerous. Metro officials said the station was not closed and warned on social media that riders should be “mindful when entering.” They also said an exhaust system was at the station and working to clear the air.

Original post at 5:59 a.m.

Some Metro riders reported smoke at the Pentagon City stop Tuesday morning.

Metro officials did not immediately confirm the reports on social media posts and TV commuter updates. It was not clear what was causing the smoke and it was not known if anyone was hurt. At least three fire trucks were reported to be on the scene. It was not clear it if it was impacting rail service.