The Mexican food chain issued the following statement.

"When health department officials in the Seattle, Washington and Portland, Oregon areas notified us that they were investigating a number of E. coli cases, including some affecting people who ate at ten of our restaurants in those areas, we immediately began taking action to respond.

Even though this investigation affected only ten Chipotle restaurants — and the majority of our locations in the area have reported no problems — we closed all Chipotle restaurants in these markets out of an abundance of caution.

We are working closely with health department officials to determine the cause of this issue. At this point no cause has been established between this issue and any ingredient. Chipotle has been conducting food and environmental testing in these restaurants and testing food at our distribution center. Additionally, health officials are testing food from the affected restaurants.

The safety of our customers and the integrity of our food supply have always been our highest priorities. We offer our deepest sympathies to those who have been affected by this situation, and will continue to cooperate with health authorities as they look to conclude the investigation.

In addition to working closely with health officials we have taken a number of steps to ensure the safety of food served in all Chipotle restaurants in the Seattle, Washington and Portland, Oregon markets. These steps include:

For more details, click here to read the full statement from Chipotle's website.