A widespread Microsoft outage linked to cybersecurity firm Crowdstrike disrupted flights, banks, media outlets and companies around the world on Friday and highlighted dependence on software from a handful of providers.

The website DownDectector, which tracks user-reported internet outages, recorded growing outages in services at Visa, ADT security and Amazon, and major U.S. carriers including Delta and United.

CrowdStrike CEO George Kurtz posted on social media platform X that the company “is actively working with customers impacted by a defect found in a single content update for Windows hosts.”

He said: “This is not a security incident or cyberattack. The issue has been identified, isolated and a fix has been deployed.”

The issue affected Microsoft 365 apps and services, and escalating disruptions continued hours after the technology company said it was gradually fixing it.

Microsoft 365 posted on X that the company was “working on rerouting the impacted traffic to alternate systems to alleviate impact in a more expedient fashion” and that they were “observing a positive trend in service availability.”

U.S. airlines were reporting major disruptions across the country. At least five U.S. airlines — Allegiant Air, American, Delta, Spirit and United — had grounded all flights for a time, according to the Federal Aviation Administration.

The issues were also being felt at airports around the world, including Hong Kong International Airport, Sydney Airport, Berlin Brandenburg Airport, Schiphol Airport in Amsterdam and Denver International Airport. 
At the Manchester Airport in Britain, there were long lines in the departures area as many machines at check-in counters were not working. Ryanair, one of the largest airlines in Europe, said it was experiencing disruption because of a third party IT outage that is “entirely out of our control.”

In the U.S., the outage appeared to be affecting emergency 911 lines in multiple states, the U.S. Emergency Alert System said on social media. It said people experiencing emergencies should call the number for their local police or fire department.

In Britain, the National Health Service was experiencing a loss of access to its computer systems across a number of hospitals and doctors offices.

Many television broadcasters also reported problems. In France, TF1 and Canal+, among the most watched, said in posts on X that it couldn’t go on air. “We’re all onstage, but there’s a gigantic breakdown in the control room” making it impossible to go live, Christophe Beaugrand-Guerrin, a TF1 presenter, wrote on X.