A city school has been forced to close for four days after a cyber attack on its IT systems. St Anne's Catholic School in Southampton messaged parents on Sunday to say its network had been hacked by ransomware, which is where viruses threaten to delete files unless a ransom is paid. The school said its IT team acted immediately to stop it spreading and reported the incident to the Information Commissioner's Office (ICO), the National Cyber Security Centre (NCSC) and police. Headteacher Julian Waterfield said the school will open on Friday and there was currently "no evidence that any data has been compromised".