Late last year, Landry’s Inc., a restaurant conglomerate with over 500 locations, confirmed that it had been hit by a credit card data breach. At the time, the group didn’t confirm how many locations were affected. Landry’s now says soon it will begin notifying customers who might’ve been affected.

Landry’s announced today that its findings show that criminal attackers installed a program on payment card processing devices at some of the properties under its umbrella. The company manages dozens of chains like Morton’s Steakhouse, McCormick & Schmick’s, and the Rainforest Cafe, as well as several hotels, resorts, and casinos, including the Golden Nugget chain.

“The program was designed to search for data from the magnetic stripe of payment cards that had been swiped (cardholder name, card number, expiration date and internal verification code) as the data was being routed through affected systems,” Landry’s said in a statement.

The company says that the payment card data breaches at its restaurants and venues happened during three periods between May 2014 and December 2015: 1.) between May 4, 2014, and March 15, 2015; 2.) between March 16, 2015 and May 4, which included “a small percentage of locations” affected; and between May 5, 2015 and Dec. 3 2015.

For a list of Landry’s Inc. properties that were affected by the data breach including the dates those locations were affected, click here.

Landry’s says in its statement that it continues to work with law enforcement investigating the breach, and has enhanced its payment security measures.

“We are also working closely with the payment card networks to identify potentially affected cards so that the card issuers can be made aware and initiate heightened monitoring of those accounts,” the company said. “For those customers we can identify as having used their card at an affected location during that location’s at-risk window and for whom we have a mailing address or e-mail address, we will be mailing them a letter or sending them an e-mail.”

Customers are also urged to remain vigilant in monitoring their card statements, and should immediately report irregularities.

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