A cyber attack has hit guests the Houstonian Hotel. At least 10,000 customers have been notified that the hotel's credit card processing system was breached.

The U.S. Secret Service first notified the hotel about breach.

According to a hotel spokesperson, the breach took place for six months between Dec. 28 and June 20.

It is unclear how many transactions were impacted, but the hotel is offering free credit monitoring to guests who stayed during that time.

The Houstonian said it is working with the Secret Service and the Houston Police Department to assist in their investigations.