The FBI is investigating the computer virus that paralyzed some of MedStar Health's hospitals and practices on Monday, March 28. 

The FBI said it was investigating whether the unknown hackers demanded a ransom from the Washington, D.C.-area provider to restore systems.

“Within 48 hours of the malware attack on MedStar Health's information system, the three main clinical information systems supporting patient care are moving to full restoration, and enhanced functionality continues to be added to other systems,” according to a MedStar statement. “We are pleased that our analysis continues to show no patient or associate data have been compromised. MedStar's IT team and cybersecurity experts have worked around the clock to protect the integrity of our clinical data systems, and to restore operations. Restoration of additional clinical systems continues with priority given to those related directly to patient care.”

The recovery of major clinical information systems followed MedStar's decision to take its systems offline to prevent the spread of the malware identified early Monday morning.

Systems that enable patients to make medical appointments are also moving toward full restoration.

MedStar said it had seen more than 6,000 patients in its hospitals and ambulatory centers, performed 782 surgeries and delivered 72 babies.

MedStar operates 10 hospitals in Maryland and Washington, including the MedStar Georgetown University Hospital, along with other facilities. It employs 30,000 staff and has 6,000 affiliated physicians.