During the past few days, national restaurant chain Chipotle Mexican Grill has closed 43 stores in the Pacific Northwest in response to an E. coli outbreak health officials linked to the company’s food.

According to the Associated Press, 37 people in Washington and Oregon have tested positive for the strain of E. coli related to the outbreak. Many of those people reported eating Chipotle in the days leading up to their illness.

As of Tuesday evening, investigators have traced the outbreak to eight Chipotle restaurants in Washington and Oregon, but the company says it decided to close a total of 43 restaurants out of an abundance of caution. A direct cause of the outbreak has not yet been determined by health officials.

The food chain says it is taking a number of immediate steps to assist in the investigation. Specifically, these steps include:

-Conducting additional deep cleaning and full sanitization of its restaurants in the area;

-Conducting environmental testing in its restaurants, and food testing in its restaurants and distribution centers in addition to testing being conducted by health department officials;

-Replacing all food items in the restaurants that are closed;

-Batch testing some ingredients before resupplying;

-Continuing to help in the investigation; and

-Retaining two food safety consulting firms to help the company assess and improve its food safety standards.

“The safety of our customers and integrity of our food supply has always been our highest priority,” says Steve Ells, chairman and co-CEO of Chipotle. “We work with a number of very fresh ingredients in order to serve our customers the highest-quality, best-tasting food we can. If there are opportunities to do better, we will push ourselves to find them and enhance our already high standards for food safety. Our deepest sympathies go out to those who have been affected by this situation and it is our greatest priority to ensure the safety of all of the food we serve and maintain our customers’ confidence in eating at Chipotle.”