IT security consultant Troy Hunt called it "the largest IT outage in history," saying, "basically what we were all worried about with Y2K, except it's actually happened this time."

The problems are ongoing, and they affect Windows users worldwide. They have taken down systems for everything from airlines to U.S. government offices to hospitals and emergency services. 

From Ars Technica: 

After cybersecurity firm CrowdStrike shipped an update to its Falcon Sensor software that protects mission critical systems, Blue Screens of Death started taking down Windows-based systems.

George Kurtz, president and CEO of Crowdstrike, a modern antivirus platform, was quick to take responsibility for the issue, writing on X, "CrowdStrike is actively working with customers impacted by a defect found in a single content update for Windows hosts. Mac and Linux hosts are not impacted. This is not a security incident or cyberattack. The issue has been identified, isolated and a fix has been deployed." 

One IT professional I know said his government laptop is completely "bricked," meaning it's unusable. He said the problems associated with this could go on for months. 

Here's what the outage looks like on affected systems: 

Emergency alert systems are down in many areas across several states. 

From the New York Times, 

President Biden has been briefed on the CrowdStrike outage, according to the White House. Administration officials are “in touch with CrowdStrike and impacted entities. His team is engaged across the interagency to get sector by sector updates throughout the day and is standing by to provide assistance as needed.”

This is a developing story.