Anne Felton, 80, of Ponte Vedra, Florida, and another woman customer were found unconscious in the toilet and other people in the restaurant were struggling to breath, the U.K. Daily Mail reports.
Felton died on Thursday morning, hours after falling unconscious in the restaurant at Pooler, Georgia, Police Chief Mark Revenew said, Reuters reported.
The fumes were believed to have been from cleaning products.
A total of 10 people, including three firefighters, were hospitalized after being sickened by the fumes in the bathroom, Pooler Fire Chief Wade Simmons said.
Firefighters noticed a smell in the bathroom but were not able to identify the source, Simmons said.
“There are a lot of theories, but there was nothing we could see, and we were unable to find the cause,” he added. “Possibly during the autopsy there will be for sure answers, but as of now, there is no definitive answer.”
When the first call was made, there was no indication that there were toxic fumes and the firefighters were sent wearing their regular uniforms, the Daily Mail reported.
“I think it went really well. We don’t like the fact they were hurt, but it started as a standard medical call not knowing what exactly was going on,” Simmons told CBS.
CBS reported that it would not be clear if Felton died from the hazardous fumes until an autopsy was done.
The owners of the restaurant said that safety was a priority and it was working to establish the cause of the incident.
“We continue to work with the local authorities to collect more information about what may have happened,” John and Monique Palamccio, the McDonald’s franchisees who own the restaurant, said in a statement.
“The safety of our customers and employees has and will continue to be our number one concern. Our thoughts and prayers remain with the families who have been impacted,” they said.
The city of Pooler is near Savannah/Hilton Head International Airport.