The state's Prime Minister Armin Laschet announced that the entire district of Guetersloh -- home to more than 360,000 people -- would be locked down for the next seven days.
Laschet said the new lockdown would mirror the measures imposed on a national level earlier in the Covid-19 pandemic.
Group meetings have been banned, and schools, daycare centers, museums, restaurants, pubs, swimming pools, gyms and other public places forced to close or drastically limit the number of people allowed in at any one time.
Meetings between members of different households have been limited to two people at a time. Shops will remain open, but only with strict hygiene measures in place.