NEW YORK (AP) — A faulty software update caused technological havoc worldwide on Friday, grounding flights, knocking down some financial companies and news outlets, and disrupting hospitals, small businesses and government offices.

The breadth of the outages highlighted the fragility of a digitized world dependent on just a few providers for key computing services.

The trouble was sparked by an update issued by cybersecurity firm CrowdStrike and only affected its customers running Microsoft Windows, the world’s most popular operating system for personal computers. It was not the result of hacking or a cyberattack, according to CrowdStrike, which apologized and said a fix was on the way.

Businesses and governments worldwide experienced hourslong disruptions — their computer monitors glowing blue with error messages — and they scrambled to deal with the fallout. CrowdStrike’s CEO said some of their systems will require time-consuming manual fixes.

Thousands of flights were canceled and tens of thousands were delayed, leading to long lines at airports in the U.S., Europe, Asia and Latin America. Airlines lost access to check-in and booking services in the heart of the summer travel season. By late afternoon Eastern time, the worst appeared to be over, though there were still lingering cancellations and delays do to the cascading effect of the disruption.

Several local TV stations in the U.S. were prevented from airing the news early Friday, and some state and local governments reported problems at courts, motor vehicles departments, unemployment agencies, emergency call centers and other offices, but as the day progressed many of the systems were getting back to normal.

Affected hospitals had problems with appointment systems, forcing them to suspend patient visits and cancel some surgeries.

Alison Baulos said her 73-year-old father’s heart surgery in Paducah, Kentucky, was canceled Friday morning because of the tech outage, leaving her family scared and worried.

“It does really make you just realize how much we rely on technology and how scary it is,” Baulos said. She said her father was waiting at Baptist Hospital to find out what will happen next.

American Express said it temporarily had some difficulties processing transactions, while TD Bank responded to online complaints by saying it was working to restore customers’ ability to access their accounts.

In New York City’s Times Square, right before 12:30 a.m., the blue “recovery” screens popping up on laptops appeared on several giant electronic billboards. A few were dark Friday afternoon.

A reminder of vulnerability

Cyber expert James Bore said real harm would be caused. “All of these systems are running the same software,” Bore said. “We’ve made all of these tools so widespread that when things inevitably go wrong — and they will, as we’ve seen — they go wrong at a huge scale.”

CrowdStrike said in a recording on its customer service line that the problem was related to “the Falcon sensor,” referring to one of its products used to block online attacks. The company says it has 29,000 customers.

In an interview on NBC’s “Today Show,” CrowdStrike CEO George Kurtz apologized, saying the company was “deeply sorry for the impact that we’ve caused to customers, to travelers, to anyone affected by this, including our companies.”

“We know what the issue is” and are working to fix it, Kurtz said. However, he noted it could take “some time” for certain customers, especially those lacking in-house expertise.

While CrowdStrike’s update was automated, the fix requires hands-on work such as deleting corrupted files, which could take some customers days or longer, said Forrester analyst Allie Mellen.

“Given that CrowdStrike has a ton of customers, a ton of Fortune 500 customers, and they have likely millions of (computers) under management, this causes a bigger issue,” Mellen said. “It is going to be a long and arduous process.”

Ann Johnson, corporate vice president and deputy chief information security officer at Microsoft, said late Friday afternoon that “at this point in time, I would say that customers are receiving or have received the necessary information they need and are getting the support they need — understanding it’s a very major issue.”

She said Microsoft’s primary focus is getting customers back online, but could not estimate how long this might take.

Shares of CrowdStrike, which is based in Austin, Texas, ended Friday trading down more than 11%. Microsoft’s stock price fell less than 1%.

Cybersecurity experts said those affected by the outage also needed to be wary of bad actors reaching out claiming they can help. “Attackers will definitely prey on organizations as a result of this,” said Gartner analyst Eric Grenier.

Air travel delayed everywhere

Thousands of flights were affected in the U.S. alone, though by late morning on the East Coast airlines said they were beginning to mitigate problems and resume some service. Unclogging the system takes time, though.

Airlines and railways in the U.K. experienced long wait times. And airports across Europe suspended landings or halted takeoffs for several hours due to difficulties in checking in passengers.

Saskia Oettinghaus, a member of the German Olympic diving team, was among those stuck at the Berlin Airport.

“We are on our way to Paris for the Olympic Games and now we are at a standstill here for the time being,” Oettinghaus said.

In Cancun, Mexico, the main tourist destination in the Caribbean coast, the state government said there were 24 cancellations and 100 delayed flights.