Firefighters have contained a gas leak at a scrap metal recycling plant in Apache Junction.
Forty homes and 20 businesses near Tomahawk and Southern Ave were evacuated.
According to Dave Montgomery, Apache Junction Fire Department spokesman, an old compressed gas cylinder was leaking acetylene, a type of gas used in welding.
"They were in the process of loading it in a boat container to take it to a metal recycling place and that's when it broke open," said Montgomery.
Workers left the property and called authorities.
Crews from Apache Junction, Mesa, Queen Creek and Gilbert arrived on scene and began evacuating homes and businesses. The area tested a high reading of hydrogen sulfide, an extremely flammable and toxic gas.
They eventually were able to seal the cylinder to slow the leak, and then stop the leak.
Meanwhile, around 5 p.m., air quality tests improved, so all residents were allowed to return to their homes.
The owner has contacted a company to remove and clean up the hazardous material. No one was hurt.