One person was killed and at least 10 others were injured when a machine used in the manufacture of electrical parts exploded and released chemical fumes, officials said.
The blast took place at the Arens Controls factory in Arlington Heights, northwestern suburb of Chicago, at about 9 a.m., NBCChicago.com reported.
The Arlington Heights Fire Department said the injuries were caused by a malfunctioning machine in an area where workers test electrical parts. Workers were using a corrosive liquid at the time, but it's not known whether that caused the explosion.
"The chemical they were using was a diluted form of potassium hydroxide," said Arlington Heights Fire Chief Glenn Erickson. "At this point in time we don't know what role the chemical had in the accident, if it had any role at all."
Officials confirmed one person was dead at the scene. Seven workers were injured and three police officers, two from Arlington Heights and one from Buffalo Grove departments, were treated for respiratory problems. The deceased worker's name and age are not yet known.
The injuries sustained by the other workers and officers were not considered life-threatening, the Chicago Tribune reported.
About 50 employees were evacuated and remained outside more than three hours after the incident as firefighters and police continued to investigate.
Police said they were waiting for occupational safety inspectors arrival before they conduct a full investigation.
"Destruction and devastation in there from the equipment that exploded," Arlington Heights police Cmdr. Kenneth Galinski told NBCChicago.com at the scene. "A lot of twisted metal."
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