A number of hospitals across England were forced to divert emergency patients after being hit by a suspected cyber attack.
According to a report by The Guardian, hospitals across the country appear to have been simultaneously hit by a bug in their IT systems, leading to many diverting emergency patients.
NHS England said it was aware of the problem and would release more details soon.
East and North Hertfordshire NHS trust, one of the those affected, said in a statement: "Today (Friday, 12 May 2017), the trust has experienced a major IT problem, believed to be caused by a cyber attack. Immediately on discovery of the problem, the trust acted to protect its IT systems by shutting them down; it also meant that the trust's telephone system is not able to accept incoming calls."
"The trust is postponing all non-urgent activity for today and is asking people not to come to A&E - please ring NHS111 for urgent medical advice or 999 if it is a life-threatening emergency," the statement added.
Meanwhile, the Independent reported that a conversation circulating online saw one doctor saying "our hospital is down".
"We got a message saying your computers are now under their control and pay a certain amount of money. And now everything is gone.