An on-going investigation is underway involving the Denver-based company, Chipotle after it has been linked to a possible E.coli outbreak, affecting people from Washington and Oregon.

According to Oregon Health Authority, 19 people from Washington and three people from Portland became sick after eating at the Mexican food chain since October 14. There have been no deaths reported but 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. having been true to their thrust of upholding integrity decided to shut down 43 branches as spokesman Chris Arnold said that the safety and well-being of their customers is always their highest priority. After receiving notifications from the state's health officials and complaints from their patrons who became sick.

"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. He also added that they will cooperate to the ongoing investigations to pinpoint the cause of the problem.

According to reports from NY Post, Washington health officials said that 17 out of 19 of those who got sick in the state were verified to have eaten ate at Chipotle.

"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 said.

Food samples from Chipotle have also been collected for testing.

"Anyone who thinks they may have become ill from eating at a Chipotle restaurant in the past three weeks should consult their healthcare provider,"  said epidemiologist Dr. Scott Lindquist in a Washington Health Department statement.

Most strains of E. coli are harmless, but can possibly cause diarrhea, urinary tract infections, respiratory illness, pneumonia and other illnesses, according to the Centers for Disease Control and Prevention. Health officials say the best defense against the bacterial illness is to thoroughly wash hands with soap and water.