Chipotle has temporarily closed 43 stores in Washington and Oregon after an E. coli outbreak was linked to several of the chain’s restaurants in the area.

Eight people have been hospitalized but no one has died from the reported cases of infection, according to the Washington State Department of Health. Health officials believe the outbreak is linked to Chipotle’s food but haven’t discovered the exact source of contamination.

“While the outbreak appears to be linked to food served at Chipotle restaurants, the food or other source of contamination hasn’t yet been determined and remains under investigation,” the Department of Health said in a statement.

Chipotle spokesman Chris Arnold said that customers’ safety is the company’s biggest concern.

“We immediately closed all of our restaurants in the area out of an abundance of caution, even though the vast majority of these restaurants have no reported problems,” he said.

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Write to Megan McCluskey at megan.mccluskey@time.com.