The 34-year-old man was working at a high-rise apartment building construction site when the accident occurred at around 4:20 p.m. local time. The construction worker was inside an elevator shaft when he suffered the injury to his arm.
According to the Chicago Tribune, rescue worker were sent to the construction site and transported him to Northwestern Memorial Hospital.
His left arm was amputated near the shoulder, reports NBC Chicago. He is in critical condition and underwent surgery on Saturday night.
According to the Occupational Safety and Health Administration (OSHA):