A grand jury is investigating the circumstances surrounding a norovirus outbreak at Chipotle. Not the recent one in Boston that sickened more than 150 people, but the August outbreak in California that left more than 100 employees and customers ill.

Chipotle told investors in a Securities and Exchange Commission filing [PDF] on Wednesday that it had received a grand jury subpoena seeking documents related to the mid-August outbreak in Simi Valley, CA.

“It is not possible at this time to determine whether we will incur, or to reasonably estimate the amount of, any fines, penalties or further liabilities in connection with the investigation pursuant to which the subpoena was issued,” the filing said.

A spokesperson for Chipotle tells CNBC that “as a matter of policy” the company doesn’t comment on pending legal actions, but that it will offer “our full cooperation” to the investigation.

In August, the Simi Valley Chipotle restaurant was closed for a short time after nearly 60 customers and 17 employees complained about feeling ill following visits to the restaurant.

At the time, the cause of the outbreak, which sent several customers to the hospital, was unknown.

Mike Byrne, Ventura County Environmental Health Division food safety supervisor, said that inspectors and specialists were following up with those who became sick to try to determine if the illnesses stemmed from a specific food problem or if changes are needed make sure food is safe.

Customers and employees reported various symptoms following their visits, including fever, diarrhea and vomiting.

One customer said that she and her sister became ill after eating at the restaurant on August. 18.

“We were throwing up, going to the bathroom. We had really bad chills,” she said. “I just want to get the answer.”

[via CNBC]

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