Chipotle Mexican Grill, Inc. (NYSE:CMG) has announced that it is investigating a 2017 data breach.

According to CFO Jack Hartung, the Chipotle data breach occurred between March 24 and April 18. It targeted the payment processing system that the company uses. CMG has already been working with authorities and cyber security firms and believes it has stopped the unauthorized activity.

Hartung announced the Chipotle data breach during the company’s earnings call for the first quarter of 2017. He says that CMG is still collecting data on the breach. As a result of this, the company isn’t ready to release more details about the breach, yet.

After more information is obtained concerning the Chipotle data breach, the company will alert affected customers. However, it can’t provide specific information, such as affected locations or times of the breach, until then, reports Consumerist.

The Chipotle data breach is a black spot on what was otherwise a strong quarter. Its earnings per share for the quarter was $1.60. This is an increase over its losses per share of 88 cents from the same time last year. It also came in above Wall Street’s earnings per share estimate of $1.27 for the quarter.

During the first quarter of 2017, Chipotle Mexican Grill, Inc. reported revenue of $1.07 billion. This is up from its revenue of  $834.46 million in the first quarter of 2016. It also beat out analysts’ revenue estimate of $1.05 billion for the first quarter of the year.

CMG stock was up 2% as of Wednesday afternoon.