Liquid nitrogen incident

 At 5:30 p.m. on February 5, 2017, an employee was responding to an emergency alarm. As he entered a space that was oxygen deficient, he was knocked unconscious. The employee was rescued from the space and was hospitalized, where he received treatment for having been exposed to an oxygen deficient atmosphere, as well as hypothermia and frostbite. His injuries resulted in amputation of an unspecified extremities. The incident investigation revealed that the space contained liquid nitrogen. 

Source:Osha.gov