The eatery in Forest City was shut down Thursday after the customers, who had ordered the drinks shortly after the restaurant opened for lunch, “immediately experienced discomfort and chemical burns in and around their mouths,” the Foothills Health District said in a statement.

“Two restaurant employees subsequently tasted the substance and reported similar symptoms,” the statement said.

It was reopened the next day after local health inspectors discovered that a worker “preparing the bar for lunch service discovered the unlabeled container and, believing its contents to be sugar, used the chemical to prepare the margarita station.”

Chili’s, according to its menu, offers several margaritas that are made with a “citrus-sugar rimmer” in addition to the traditional salt.

Health District spokesperson Megan Rollins said in an email the investigation was closed and no fines were issued. She said the injured people received medical treatment, but she had no information about their conditions.