Three people in the Portland area and 19 people in Washington became sick after eating at the Mexican food chain since Oct. 14, the Oregon Health Authority said.
No deaths have been reported and eight people have been hospitalized.
“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 Washington Department of Health said in a statement.
Chipotle Mexican Grill Inc. spokesman Chris Arnold said the safety and well-being of customers is always its highest priority.
He said Chipotle was notified by health officials that they were investigating E. coli cases that included people who became sick after eating at six restaurants.
“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,” Arnold said in a statement.
The Denver-based company said 43 Chipotle sites have been closed in the two states. Chipotle operates more than 1,700 restaurants in the U.S. and elsewhere.