(CHICAGO) South suburban commuters might want to rethink their travel plans as an early Wednesday derailment downtown is causing “extensive” delays for Metra Electric District trains during the Wednesday morning rush.

Train No. 150 derailed at the 11th Street station about 1 a.m., Metra spokesman Tom Miller said. Two cars slipped off the tracks, but remained upright.

The derailed cars are blocking two of three tracks that run through the area, which means all inbound and outbound trains will have to operate on a single track until the derailment is cleared, Miller said. Delays are expected to range from 30 to 60 minutes during the morning rush.

Crews continued to work to clear the tracks as of 4 a.m., although it was not immediately clear how long it would take, according to Miller.

Metra urges riders to listen to platform announcements and monitor its website for updates.