(translation from WDR):
The city of Paderborn’s ‘Lernstatt’ network has become the target of a major hacker attack. The cyber attack paralyzed numerous mail accounts and web conferences.
On Friday morning there were around 20 million accesses in just under half an hour, mainly to mail traffic and web conferences.
17,000 student and 2000 teacher accounts are affected. Because of the massive attacks from the Internet, the IT system of the learning center is currently still not working.
Source: WDR.de
h/t, @Chum1ng0