UPDATED 05/19/12 12:03 p.m.

CHICAGO (CBS) — The Metra Electric and South Shore lines were shut down for over an hour in the Hyde Park neighborhood Saturday morning for a suspicious suitcase that turned out to be empty.

CBS 2’s Kris Habermehl reports the line was shut down as a precautionary measure near the 55th/56th/57th Street stop.

A suspicious suitcase was found under the underpass beneath 57th Street, which is located a few blocks east of the University of Chicago campus and just west of the Museum of Science and Industry.

A witness called police after seeing two men leave the suitcase in the area around 57th Street.

Police and other law enforcement officials – including federal agents – were on the scene Saturday morning. Bomb-sniffing dogs were also dispatched.

The suitcase turned out to be empty, and investigators gave the all clear around 10 a.m.

An inbound South Shore train was halted just out of the station, and all the passengers were taken off and placed under police supervision. The Northern Indiana Commuter Transportation District halted its trains while the investigation was ongoing. Metra also stopped its trains.

A total of three trains were halted for a while.

The Metra Electric line runs directly under McCormick Place, where the NATO Summit is being held on Sunday.

In addition, 57th Street was closed at the scene, and Lake Park Avenue parallel to the Metra Electric tracks was closed.

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