Nursing home and senior living community operators were scrambling to assess possible damage and weigh care interruptions Friday, in the wake of a widespread technology outage.

Cybersecurity giant CrowdStrike said a bug in an update sent to Microsoft’s Windows operating system was the culprit.

Officials in at least three states warned of related 911 problems in their areas. Beyond senior living and healthcare, infrastructure sectors such as banks and airports were affected. At press time, senior care operators had reported that their systems remain largely unaffected, and they would maintain essential services for residents. Some operators, however, warned that service delays might be caused by records being unavailable.

In fact, several hospitals and medical centers were turning patients away as a precautionary measure. Mass General Brigham in Boston announced it would cancel “all previously scheduled non-urgent surgeries, procedures, and medical visits.”

The University of Miami Health System said that its facilities were open but warned that there would be delays due to computers records being unavailable.

CrowdStrikeCEO George Kurtz has since said that the company is “actively working with customers impacted by a defect found in a single content update for Windows hosts,” stressing that Mac and Linux hosts are not affected.

“This is not a security incident or cyberattack. The issue has been identified, isolated and a fix has been deployed,” he posted on social media.

CrowdStrike is a leading provider of cloud-based security technology.