DENVER – An E. coli incident linked to Chipotle locations in Washington and Oregon was likely caused by contaminated produce, reports CNBC.  

According the health officials in Oregon, the E. coli incident at the fast-casual chain has sickened 37 people, up from previous estimate of at least 22 people, and that most of these people ate at Chipotle restaurants. The E. coli episode has led to the temporary closure of 43 Chipotle Mexican Grill restaurants in the Pacific Northwest.

"We are looking at everything but our epidemiology investigation is guiding us toward produce," Jonathan Modie, a spokesman for the Oregon Public Health Division, told CNBC. "Chipotle has meat products, but based on things we heard from people who got sick...it seems like the most common denominator is some kind of vegetable course."

Chipotle spokesman Chris Arnold said the company has closed all of its stores in Oregon Washington "out of an abundance of caution" after health officials informed them of the situation. Arnold told CNBC that so far only customers who ate food from eight of those restaurants have reported becoming ill.

"Produce is certainly a possibility, but we are not going to speculate on what the cause may be while the investigation is going on," Arnold told the news source, adding, "Right now, getting through the investigation is the priority and we continue to offer our full cooperation as that moves forward."

This is the third time this year Chipotle has faced a major food safety scare. Bill Marler, a Seattle-based attorney who specializes in food safety cases, told CNBC that Chipotle could be in danger of damaging its brand.

"If I was the Chipotle CEO, I would be having my food safety team in my office yesterday asking, ‘What happened and what do we need to do to make sure this doesn't happen again?’” he said. “I guarantee the cost of any change they need to make to make their food supply safer pales in comparison to the losses they have had in just the last 24 hours on their stock price.”