Five people suffered chemical burns after drinking margaritas rimmed with a white granulated substance misidentified as sugar at a Chili’s Grill & Bar in Forest City, N.C., a health official said.

The people who fell ill on Wednesday were three customers and two staff members who appeared to have been burned largely on and around their mouths, Megan Rollins, a spokeswoman at Foothills Health District, said in an interview on Saturday.

She said they sustained the injuries after contact with a degreaser, which had been left in an unlabeled container near the bar.

The district, which is responsible for food safety, immediately dispatched environmental health specialists to investigate the restaurant, Jason Masters, the public health director at Foothills Health District, said in an email.

The Forest City Police Department could not be reached on Saturday. It was unclear whether it had opened an investigation.

A representative for Chili’s said in a statement that the restaurant chain “took immediate action to support those affected and avoid further injuries.”

The chemical, which was not identified by name or brand, was brought into the Chili’s early on Oct. 26 by a contractor who had been hired to power wash the building’s exterior, Ms. Rollins said. The contractor was not identified.

That worker then handed the product to a restaurant employee, who left it by the bar. It wasn’t clear why the contractor gave the employee the product, Ms. Rollins said.

On Wednesday, another employee, who was prepping the bar before lunch service, discovered the product and placed some of it in containers at the margarita station.

Oops!