Fast food chain Chipotle warned customers through a notice on its website on Tuesday that it is investigating a breach of the network that supports payment processing for  purchases made in the company’s restaurants.  

“…we recently detected unauthorized activity on the network that supports payment processing for purchases made in our restaurants,” the company stated.

The company said it has enlisted the help of “leading” cybersecurity firms, law enforcement and their payment processor to investigate the breach.

“Our investigation is focused on card transactions in our restaurants that occurred from March 24, 2017 through April 18, 2017. Because our investigation is continuing, complete findings are not available and it is too early to provide further details on the investigation. We anticipate providing notification to any affected customers as we get further clarity about the specific time frames and restaurant locations that may have been affected.”

The company has asked customers to closely monitor their card statements and to notify their banks in the event of any unusual activities.