Washington, DC –

“Firefighters Melvin Batts and Sam Acala had popped into a Subway restaurant near Greenbelt and Good Luck roads around noon when the carbon monoxide detectors strapped to their walkie-talkies went off…’The readings we found were as high as 600 ppm’…The shopping center was immediately evacuated, and firefighters suited up to find the leak. Emergency crews found that the exhaust vent from an air conditioning unit was broken and funneling carbon monoxide into stores instead of outside.”

https://www.washingtonpost.com/local/public-safety/two-firefighters-wanted-sandwiches-they-saved-people-from-carbon-monoxide-poisoning-instead/2016/10/14/a69dcb52-9250-11e6-9c85-ac42097b8cc0_story.html