Casino company Caesars Entertainment on Thursday joined Las Vegas gambling rival MGM Resorts International in reporting that it was hit by a cyberattack, but added in a report to federal regulators that its casino and online operations were not disrupted. The Reno-based publicly traded company told the federal Securities and Exchange Commission that it could not guarantee that personal information about tens of millions of customers was secure following a data breach Sept. 7 that may have exposed driver’s license and Social Security numbers of loyalty rewards members. “We have taken steps to ensure that the stolen data is deleted by the unauthorized actor,” the company said, “although we cannot guarantee this result.”