CHICAGO (CBS) — After commuters had to deal with nearly four hours of major delays on the Blue Line, due to a power outage on tracks near a downtown subway station, CTA officials said service was returning to normal Wednesday afternoon.

Around 8:15 a.m., power went out to subway tracks near the LaSalle station on the Blue Line, stalling at least two trains.

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A Fire Department spokesman said the two stalled trains were evacuated, and passengers were taken out of the station.

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After the track outage, Blue Line trains were operating on a single track between the LaSalle subway station and the Western station on the Forest Park branch, causing significant delays across the system. The CTA ran shuttle buses between LaSalle and Western in an effort to help ease the problem.

Shortly before 12:15 p.m., the CTA said normal service was resuming on the Blue Line, though with residual delays.

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Officials have not said what caused the tracks to lose power near LaSalle.