CHICAGO (CBS) — Red Line service was returning to normal Thursday morning, about an hour after the CTA began rerouting Red Line trains to elevated tracks due to reports of smoke in the subway.

Around 9:40 a.m., Fire Department crews responded to reports of smoke in the Red Line subway.

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No trains were evacuated, and no injuries were reported, but power was shut off to the subway tracks while Fire Department and CTA crews investigated. Several Fire Department and Police Department vehicles were stationed outside the Jackson Red Line subway station Thursday morning.

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Red Line trains were rerouted to the elevated tracks between the Fullerton and Cermak/Chinatown stations as CTA and Fire Department crews investigated.

The CTA said normal service was resuming on the subway at 10:30 a.m.

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The Fire Department said the source of the smoke was unknown. The CTA was investigating.

Chicago Police and Fire Department crews respond to reports of smoke in the Red Line subway downtown. (Credit: CBS)

Chicago Police and Fire Department crews respond to reports of smoke in the Red Line subway downtown. (Credit: CBS)