Transcript for Construction workers fall ill -- possibly from carbon monoxide poisoning

We're going to turn now to an unfolding scene in New York City. A carbon monoxide emergency. Several patients are being treated on the scene. Authorities say the readings were 750 parts per million, ten parts per million is considered dangerous. Here's ABC's gee Jeon Benitez. Reporter: Tonight, the New York City fire department rushing to a construction site, working frantically to extricate several workers after they became sick from carbon monoxide exposure. Multiple victims in a confined space. Can we have multiple ambulances? Reporter: First responders putting victims on stretchers, using a crane to lift some of the injured to safety. From above, you can see the dangerous situation both the workers and firefighters faced. Firefighters using plywood to make a makeshift bridge over the open construction site and reach them. Officials say workers were using power tools off a generator with improper ventilation. You're not supposed to be using gas-powered generators indoors below grade. They're supposed to be outside in a well-ventilated area. Reporter: At least nine were injured. And David, workers tested the nearby buildings and structures to see if any of that carbon monoxide has spread. Thankfully, they are not finding that odorless gas in any of those surrounding buildings. David? Gio Benitez tonight.

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