One person was killed and 10 others were sickened in a chemical accident at a Buffalo Wild Wings restaurant Thursday in Burlington, Massachusetts, authorities said.

A restaurant employee was rushed to a hospital after being exposed to sodium hypochlorite, a powerful cleaning agent, and died shortly thereafter, Michael Patterson, assistant chief of the Burlington Fire Department, told reporters. The worker told firefighters that he was feeling nauseous after breathing in fumes.

"Anyone who was in the restaurant at the time and believes they may be impacted by the incident should seek medical treatment immediately," the fire department said in a statement.

The building was evacuated at about 6 p.m. for a Tier 1 hazmat incident, Patterson said.

Two customers and eight other employees were treated at hospitals, Patterson said. They were believed to have not been seriously stricken, he said.

Download the NBC News app for breaking news

"What we believe happened is a worker at Buffalo Wild Wings used a cleaning agent on the floor. The cleaning agent is Super 8. The chemical definition or chemical identification is sodium hypochlorite," Patterson said. "What sodium hypochlorite is a high concentration of chlorine."

The fire department said that there was no active threat to public safety and that the investigation was ongoing. It said the federal Occupational Safety and Health Administration had been notified.

Buffalo Wild Wings said in a statement that it was referring questions to local authorities.

"We are shocked and saddened to learn of this horrific accident at our franchise-owned sports bar and are working closely with our franchisee and the authorities while they conduct an investigation," the company said.