Columbus, Ohio (AP) -- Officials say workers have been cleared to return to an industrial area in Columbus about six hours after a gas leak forced about 4,000 to evacuate.
Fire battalion chief David Whiting says firefighters were called at about 8 a.m. to Heartland Petroleum after a leak of hydrogen and hydrogen sulfide.
Whiting says emergency medical crews treated three people complaining of respiratory issues and took one to a hospital after a gasket failed on tank used to recycle oil.
He says a gas cloud has dissipated and the air is safe in and around the plant.
It remains closed as crews wait for the temperature of the oil drop.
The Occupational Safety and Health Administration and the Environmental Protection Agency are investigating.
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