LONDON (CBSNewYork/CBSNews) — Friday’s global cyber attack targeted Microsoft operating systems on computers across 100 countries.

Now, the company is offering free security fixes to everyone affected.

As CBS News’ Jonathan Vigliotti reported, the virtual attack sent the United Kingdom’s National Health Care Service into emergency mode. Ambulances and patients were turned away from hospitals across the country after malicious software crippled their computer systems, making access to patient records impossible.

“They said, ‘I’m really sorry, but the computer system is down. You’re going to have to go away. We can’t have any appointments, it would be dangerous to do so, because we can’t access any of the files,'” Emma Simpson, the mother of a sick child, said.

Hackers encrypted those files, rendering them unreadable. To decode them, hackers demanded $300 in ransom, then the amount would double after three days. If ignored, they warned data would be destroyed.

The malware program appeared to exploit a vulnerability in Microsoft Windows first identified by the U.S. National Security Agency and later leaked in a series of stolen documents.

The hack wasn’t just limited to computer systems in the UK. Businesses across Europe, including Spain’s telephone system, were targeted. Japan, Turkey and the Philippines were targeted as well.

In the United States, FedEx was hit.

The brunt of the attacks was felt in Russia, including the country’s largest mobile phone company.

In the UK Saturday night, goverment officials said computer systems were almost completely up and running again, Vigliotti reported. It’s unclear who’s behind the attack, but experts say it appears to be the work of cyber criminals, not state sponsored.

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