Police, fire and hazardous materials crews responded to Baltimore's Penn Station Monday evening after a white powdery substance was found on a train inbound from Washington.

Baltimore Fire Capt. Roman Clark said the powder found on the 5:05 p.m. MARC train from Washington was tested and found to be non-hazardous. A conductor making an announcement in D.C. rapped a faulty microphone against a wall, causing the powder to fall. Hazmat crews were then alerted, Clark said.

Officials did not identify the substance.

Police said the train was being checked, but that schedules were not impacted.

Passengers were moving freely throughout the station around 7:30 p.m. Monday.