The sandwich shop chain Jimmy John's announced to customers of a security breach that spanned the last three months.

Over 200 locations were affected by the breach, in which credit and debit card information was stolen; however, the company reassured the public that the breach had been fixed and it was safe to use cards again in the stores.

The company released the announcement on Wednesday when they explained how around 216 stores from all over the country had credit and debit card information stolen. Jimmy John's, a sandwich shop chain based out of Champaign, Illinois, explained they had become aware of the breach back in July 30 and hired "third party forensics experts" to help them find the breach and secure it.

Security breaches happened between June 16 and Sept. 5, the statement explained, but they were limited to stores' "point-of-sale systems," otherwise known as the card-swiping machine.

"Cards impacted by this event appear to be those swiped at the stores, and did not include those cards entered manually or online. The credit and debit card information at issue may include the card number and in some cases the cardholder's name, verification code, and/or the card's expiration date. Information entered online, such as customer address, e-mail, and password, remains secure," the statement said.

The company released a list of the affected stores along with time during which each store's security was affected. Jimmy John's has implemented new security systems, including new "encryption swipe machines," and a review of third party vendors' policies and procedures.

According to the Huffington Post, Jimmy John's mention of third party vendors could point to another company. Signature Series makes card-swiping machines and could be the source of Jimmy John's troubles.

Cybersecurity expert Brian Kerbs pointed out back in late July that Jimmy John's card security had been compromised because Signature Series had been attacked.

In a blog post, Krebs explains that Jimmy John's had asked new franchises to use Signature Series readers before they became aware of the breach. The company has not returned calls for comment.