NHS Digital, which oversees hospital cybersecurity, says the attack used the Wanna Decryptor variant of malware, which holds affected computers hostage while the attackers demand a ransom.
NHS Digital says the attack "was not specifically targeted at the NHS and is affecting organizations from across a range of sectors."
The attack is causing canceled procedures and appointments at hospitals across England. NHS Digital says 16 NHS organizations report being hit.
Hospitals across England have canceled appointments and turned away patients after suffering an apparent cyberattack.
Hospitals in London, northwest England and other parts of the country reported problems with their computer systems Friday. They asked patients not to come to the hospitals unless it was an emergency.
Pictures posted on social media showed screens of NHS computers with images demanding payment of $300 worth of the online currency Bitcoin, saying: "Ooops, your files have been encrypted!"
NHS Merseyside, which operates several hospitals in northwest England, tweeted that "following a suspected national cyberattack, we are taking all precautionary measures possible to protect our local NHS systems and services."
Bart's Health, which runs several London hospitals, said it had activated its major incident plan, cancelling routine appointments and diverting ambulances to neighboring hospitals.
Earlier Friday, The Spanish government released a statement, saying that a large number of Spanish companies were hit by hackers who planted malware in their computers