SEATTLE >> An investigation was underway Saturday in an E. coli outbreak linked to Chipotle restaurants in Washington state and Oregon, health officials said.

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 wellbeing 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 company said 43 Chipotle sites have been closed in the two states.

Chipotle will work with health officials to determine when to reopen the restaurants and to find the cause of the problem, Arnold said.

Jonathan Modie, a spokesman with the Oregon Health Authority, said many people may not see a doctor after becoming ill, so the number of people sickened in the outbreak is likely higher. People who become sick with vomiting and bloody diarrhea, and who ate at a Chipotle between Oct. 14 and 23 should see their health care provider, officials said.

People have reported symptoms of infection in Clackamas and Washington counties in Oregon, and Clark, King, Skagit and Cowlitz counties in Washington, Modie said.

There are hundreds of E. coli and similar bacteria strains in the intestines of humans. Most are harmless, but a few can cause serious problems.

Symptoms of E. coli infection include diarrhea, abdominal cramps, nausea and vomiting. Health officials say the best defense against the bacterial illness is to thoroughly wash hands with soap and water.