The news sent Chipotle’s (CMG) shares tumbling almost 10% in Friday afternoon trading, as the restaurant chain had hoped it could move forward from the outbreak.

The outbreak, which originally led to the closure of 43 restaurants in Oregon and Washington, has also seen people infected with E. coli in California, Minnesota, New York and Ohio. The CDC reports that 45 people have been infected with E. Coli across those six states. It is likely that one common item or ingredient served at the Chipotle restaurants is likely the source of the outbreak, the CDC said. Previously, the CDC had reduced the number of cases from 50 to 37 on November 18, with 24 in Washington and 13 in Oregon. It now stands at Washington (26), Oregon (13), California and Minnesota (2 each), and New York and Ohio (1 each).

The E. coli outbreak also led to Chipotle’s shares to decline earlier this month, after it was first reported that an outbreak had occurred in the northwest. At the time, analysts expressed concerns that the company could experience a sales dip in the fourth quarter, as national headlines could result in some diners staying away from the chain for a short period of time. Chipotle has already faced legal action related to the outbreak.

“We take this incident very seriously because the safety of our food and well being of our customers is always our highest priority,” said Chipotle Chairman and co-CEO Steve Ells in a statement on Friday. He apologized to those who had been affected.

Chipotle, which earlier this month reopened the 43 locations it had closed in the northwest, has vowed to work with health authorities during the investigation and also hired food safety scientists to help the company assess and improve its “already high” standards for food safety. Chipotle said it deeply cleaned the restaurants that were linked to the E. coli incident and promised to take similar actions in response to the newly reported cases. It also replaced ingredients and changed food preparation procedures.