Microsoft outage live: Huge hospital group is forced to cancel surgeries as thousands of flights are grounded and New York Subway control room loses track of its own trains

Mass General Brigham - one of the biggest healthcare systems in America - has axed all non-urgent visits, procedures and surgeries amid a global IT failure.

Hospitals were thrown into chaos overnight when the outage knocked out Windows systems around the world, knocking computers and medical devices offline and forcing medical staff to revert to pen and paper.

Mass General Brigham in Boston - which sees 2.5million patients a year - said its clinics and ERs would continue provide care to patients who have urgent health problems.

'We continue to care for all patients currently receiving care in our hospitals,' the healthcare provider added.

'We have dedicated every available resource to resolve this issue as quickly as possible, and we apologize for the inconvenience this has caused our patients.

'It is our highest priority to ensure that our patients receive the safest care possible.'

Tufts Medical Center and South Shore Health were also experiencing issues linked to the global tech outage.

Transport officials in New York say they are unable to track the location of their subways amid the outage.

While dispatchers can still see the trains and there are no safety concerns, many passengers have been left in the dark.

Crowdstrike deployed a fix at around 5:30am ET for an issue that caused the 'most serious IT outage the world has ever seen.'

The cybersecurity firm is now working to reboot its systems, which could take some time for them to fully recover.

CEO George Kurtz said the issue is 'not a security incident or cyberattack' but is a 'defect' in a 'single content update for Windows hosts.

'The issue has been identified, isolated and a fix has been deployed.'

The outage was triggered by a faulty update to its Falcon Sensor software.

Microsoft acknowledged the Windows meltdown, saying: ‘We are aware of an issue affecting Windows devices due to an update from a third-party software platform.

‘We anticipate a resolution is forthcoming.’

The outage has had an impact on some Metropolitan Transportation Authority (MTA) customer information systems, according to officials. The glitch means countdown clocks and information boards are not functioning.

Trains and buses should not be affected, but passengers are advised to listen out for updates.

The New York and New Jesery Port Authority said it has not been affected, but is advising customers not to head to the airport unless flight status has been confirmed

Georgia's Atlanta International Airport is currently the worst hit by travel disruption, with 37 cancelled flights and 58 delays, according to Flight Aware's Misery Map.

Charlotte Douglas International Airport in North Carolina is the second worst affected, with 17 cancellations.

New York City's La Guardia had grounded 13 flights as of Friday morning, with dozens more delays.

Around one in 20 flights originating in the US have been cancelled already, with almost 19,000 total delays.

American Airlines says its flights are returning to normal, but other major carriers such as Delta, Allegiant, Spirit and Frontier are still grounded.

The FAA said it is 'closely monitoring a technical issue impacting IT systems at U.S. airlines'.

At New Jersey's Newark International Airport where around 600 flights leave daily, the departures monitor was completely blank and displayed a blue error screen.