"You don't want to be paranoid, but at the same time, you still have to protect yourself and your family," said Bill McCann, an employee at KIMA who was hospitalized at Regional last year.
McCann's worried that his personal information might have gotten into the wrong hands.
"The fact that they have that information, whoever it is, whatever they plan on using it for, is a little scary," he said.
Community Health Systems says about 4.5 million patients across the country are affected. It says anyone who was referred for or received services from physicians affiliated with the company in the past five years is at risk.
Patient names, addresses, birth-dates and social security numbers were stolen. Credit card numbers and medical information were not.
In a statement to Action News, Yakima Regional Hospital says, "We take very seriously the security and confidentiality of private patient information and we sincerely regret any concern or inconvenience to patients."
It also says patients affected by the breach will get a letter and will be offered free identity theft protection. However, Regional is optimistic its patients will not be impacted and the data will not be used.
"Some of these people are really frail and the last thing you want to see is those people get hurt," McCann said.
Community Health Systems executives believe the cyber attacks happened in April and June of this year. They think an "Advanced Persistent Threat" group originating from China is responsible. Community Health Systems is working with federal authorities.