A Chipotle restaurant in Massachusetts temporarily shut down on Tuesday after four employees became ill, the company said.

The Mexican restaurant chain voluntarily closed its store in Billerica, Mass. for a “full sanitation,” Chipotle spokesman Chris Arnold told TIME in a statement.

One of the workers reportedly has a confirmed case of Norovirus, and two other employees are suspected of having the virus, according to 7News, citing the town’s health department. Chipotle said it could not confirm the diagnosis.

“We do not know if the employees are ill with Norovirus and no customers illnesses are connected to this restaurant,” Arnold said. “Any employees who reported feeling ill will be held out of the restaurant until they fully recover.”

The temporary closure comes as the company attempts to recover from a Norovirus outbreak and a string of other health scares that sickened customers and tarnished its reputation late last year. The illnesses prompted Chipotle to close all of its stores nationwide for a staff meeting last month in which executives outlined the steps the chain is taking to ensure the safety of its food.

Norovirus causes inflammation in the stomach or intestines and leads to stomach pain, nausea, diarrhea or vomiting, according to the Centers for Disease Control and Prevention.

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