Sonic: 'unusual activity' on some credit cards

NEW YORK (AP) — Sonic says there's been some "unusual activity" on credit cards used at some of its restaurants.

The fast food chain said in a statement that its credit card processor told them about the incident last week and that it's now "working to understand the nature and scope of this issue." It did not disclose how many credit cards were potentially involved in the incident or when the incident took place.

There are more than 3,500 Sonic restaurants in 44 states, according to the company's website.

Sonic said that it is working with third-party forensic experts and law enforcement officials on the incident. The potential breach at Sonic was initially reported by Krebs on Security.