CHICAGO (AP) — A commuter train partially derailed at Chicago’s Union Station, prompting officials to warn of delays.

No injuries were reported when the third, fourth and fifth cars of an eight-car Metra train derailed late Tuesday on the south side of the station. Metra says three passengers were on the train. All of the cars remained upright and the locomotive on the SouthWest Service train stayed on the tracks.

The cause of the derailment wasn’t immediately known. Crews worked Wednesday morning to remove the train and officials say several switches were damaged.

Metra says delays of up to 30 minutes are expected for passengers on the BNSF, SouthWest Service and Heritage Corridor lines in the morning. Evening trains also will be affected.

Amtrak says its trains also are expected to be delayed.