FOREST PARK, Ill. (WLS) -- A ComEd contractor was seriously injured and thousands were left without power after a chain-reaction construction accident in the western suburbs.Forest Park police said workers were using a crane to lift a metal utility pole onto its base near 16th and Circle Ave. in Forest Park when the accident took place Thursday afternoon.Officials said the worker was knocked from a cherry picker after the tower fell from the crane and struck live power lines. The power lines then struck a cherry picker, knocking the worker to the ground and causing two poles to snap.Witnesses told police the cherry picker was extended at least 30 feet off the ground at the time of the accident.The worker was rushed to a Loyola University Medical Center. Information on the worker's condition was not immediately available.ComEd said at one point, more than 2,000 customers were without power in the area. Service has since been restored to all customers.ComEd said it is cooperating with investigators to determine the cause of the accident.