A Buffalo Wild Wings employee died and at least 10 people checked themselves into hospital after being exposed to a strong chemical cleaning agent at a restaurant in Burlington, Massachusetts, authorities said on Thursday.

The Burlington fire department responded to a chemical reaction in the kitchen area of the restaurant where a male employee was suffering from nausea, a fire department representative said in a statement.

Media identified the chemical as sodium hypochlorite, a cleaning agent.

“The employee was taken to Lahey Hospital and Medical Center in serious condition after being exposed to a strong cleaning agent. The man later died at the hospital,” the department said.

The other patients, including restaurant employees and patrons, complained of difficulty in breathing and burning eyes, the department said.