Hackers demanded a ransom from two more Southern California hospitals last week and federal authorities are investigating the case . Prime Healthcare Services Inc. , a fast - growing national hospital chain , said the attackers infiltrated computer servers on Friday at two of its California hospitals , Chino Valley Medical Center in Chino and Desert Valley Hospital in Victorville . The company said the cyberattack had not affected patient safety or compromised records on patients or staff . Two sources familiar with the investigation said the hackers had demanded a ransom to unlock the hospital computer systems , similar to what happened last month at Hollywood Presbyterian Medical Center in Los Angeles . Hollywood Presbyterian said it paid $ 17,000 in bitcoin to hackers to regain access to the institution 's computers . Fred Ortega , a spokesman for Prime Healthcare , declined to comment on whether Prime received a ransom demand or paid any money , citing the ongoing investigation . " This is similar to challenges hospitals across the country are facing , and we have taken extraordinary steps to protect and expeditiously find a resolution to this disruption , " Ortega said . " The concern now is to let law enforcement do their thing and find the culprit . " FBI spokeswoman Laura Eimiller said Tuesday " we are investigating a compromise of the network at these locations . " She declined to discuss specifics of the case . The FBI also has been investigating the attack at Hollywood Presbyterian . Ortega said the two hospitals affected remain operational and steps are being taken to restore their computer systems to full functionality . He said some IT systems were shut down by hospital staff as a preventive measure so malicious software did n't spread further . hacker - computer - code - e1458648376542The company said it 's working with data security experts and the California Department of Public Health on the matter . Prime Healthcare , based in Ontario , Calif. , has acquired struggling hospitals across the country and has become one of the nation 's largest health systems . It runs 42 hospitals in 14 states . The company is led by its outspoken chairman and chief executive , Dr. Prem Reddy . A series of high - profile data breaches in the past year have raised fresh questions about the ability of hospitals , health insurers and other medical providers to safeguard the vast troves of electronic medical records and other sensitive data they are stockpiling on millions of Americans . ;