Cybersecurity firm CrowdStrike says "a significant number" of devices that were impacted by a global IT outage on Friday are now back online.
In a social media post, the company - whose faulty security update caused Microsoft Windows computers to crash around the world - added it "continues to focus on restoring all systems".
Microsoft has estimated that the incident, which is being described as one of the worst IT outages in history, impacted 8.5m computers around the world.
Businesses, banks, hospitals and airlines were among the worst-hit, with some still struggling to fully restore their systems.
"We understand the profound impact this has had on everyone. We know our customers, partners and their IT teams are working tirelessly and we’re profoundly grateful," CrowdStrike said.
"We apologise for the disruption this has created."
The firm also said it is deploying a new fix that it hoped would speed up the recovery of computer systems.
However, CrowdStrike did not say how many devices were still being impacted.
More than 1,400 flights, into or out of the US, were cancelled on Sunday, according to aviation tracking and data platform FlightAware.
Delta and United Airlines were the worst affected US airlines.
Health services in Britain, Israel and Germany were also impacted on Friday, with some services cancelled.
The massive outage has put a spotlight on the vulnerability of global computer networks, showing how a single glitch can cause global chaos.
"All too often these days, a single glitch results in a system-wide outage, affecting industries from healthcare and airlines to banks and auto dealers" said the Chair of the US Federal Trade Commission, Lina Khan, in a social media post.
"These incidents reveal how concentration can create fragile systems."
Until this incident the company had been one most trusted brands in the cybersecurity industry.
According to CrowdStrike's website, it has 29,000 customers around the world, including some of the biggest companies in the US.
One major economy largely unscathed by the outage was China, as CrowdStrike is not widely used in the country.
China is also not as reliant on Microsoft as the rest of the world.
Source: BBC
