Microsoft and the cybersecurity firm CrowdStrike have issued fixes for the global outage impacting computers running the Windows operating system, though issues still linger as the outage has forced major airlines to ground flights, disrupted television and put banking services offline.

The outage has been blamed on a software update by cybersecurity firm CrowdStrike, which has resulted in many Windows systems experiencing the dreaded “Blue Screen of Death” (BSOD) while booting.

The underlying issue causing outages for Microsoft’s 365 apps and services—including Outlook, Teams and Office—has been fixed, the company said, though a “residual impact” is continuing to affect some services.

CrowdStrike president and chief executive George Kurtz said the company was “actively working” with customers impacted by an issue found in a content update on Windows computers, adding the “issue has been identified, isolated and a fix has been deployed.”

Microsoft said it is aware of the issue affecting machines running Windows, and noted it is affecting systems running CrowdStrike’s Falcon security software. The U.S. Emergency Alerts System said 911 lines in multiple states were down.

According to the Federal Aviation Administration, nearly all major American carriers—including Delta, American and United—have been forced to temporarily ground all their flights due to the outage, while carriers and airports including Air India, KLM, Hong Kong International Airport, Berlin Brandenburg Airport and London Stansted also reported disruptions, forcing some of them to rely on manual check-ins with long queues being reported.

The London Stock Exchange group said its workspace platform was also facing an outage preventing it from publishing statements while banks and payment terminals in Australia were also affected, though the New York Stock Exchange reportedly said its systems were unaffected.

Microsoft chief executive Satya Nadella said CrowdStrike “released an update that began impacting IT systems globally,” and the company is “working closely with CrowdStrike and across the industry to provide customers technical guidance and support to safely bring their systems back online.”