BALTIMORE (WJZ) — Police shut down Baltimore’s Penn Station for hours Thursday evening after receiving reports of a suspicious package.

It’s unclear exactly what the suspicious package was or may have contained, but it was enough to prompt police to stop all train traffic into and out of the station and evacuate half the building during the busy rush hour commute.

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All trains at the station were being held; as of 6:15 p.m. the tracks had reopened, Baltimore police said.

Police were headed to the last track with dogs, WJZ’s Annie Rose Ramos reported. Later, police were seen using robots and bomb squad gear.

A portion of the lobby leading to the last track was evacuated and travelers were pushed to the entrance and side corridors.

One passenger said she was quickly evacuated from her train that was headed north.

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Another passenger said he was on a 3:45 p.m. train to D.C. when police told him to quickly evacuate the train. He ran out and spent hours waiting. Other passengers debated whether to take an Uber to destinations as far away as New York.

“A voice came on the PA system and said everyone needs to get off the train immediately,” passenger David Pontious said. “When we were leaving, we saw Amtrak police.”

MARC Penn Line had been advancing trains as far north of Union Station in D.C. as possible. The extent of the delay is still unknown.

By Thursday night, most of the delays had cleared.

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Amtrak said it’s working closely with police to investigate the incident.

Annie Rose Ramos