A Buffalo Wild Wings general manager died and 13 workers and patrons were sickened after being exposed to a toxic mixture of cleaning agents at a Massachusetts location on Thursday evening, the authorities said.

The Fire Department in Burlington, about 12 miles northwest of Boston, responded to calls at the restaurant and found a man outside being treated by paramedics, Assistant Fire Chief Michael Patterson said at a news conference on Thursday.

The episode occurred after a restaurant employee mixed an acidic detergent called Scale Kleen with a bleach-like cleaner sold as Super 8 to clean the kitchen floor, causing a chemical reaction, the authorities said.

That person, who the authorities said was not the manager who died, exited the restaurant to get fresh air.