A tornado caused "severe damage" as it tore through the western German town of Lippstadt before wreaking havoc in the nearby city of Paderborn on Friday evening, local officials said.
Numerous roofs were blown off and trees downed by the powerful storm, but so far there have been reports of deaths or injuries in Lippstadt.
But several people were reported to have been wounded in Paderborn, located about 35 kilometres west, fire officials said.
"It's chaos here right now," a Paderborn police spokeswoman said, describing damaged buildings and overturned trees.
At the Cabrioli swimming pool in Lippstadt, about 120 bathers were temporarily trapped because fallen trees blocked the entrance. They were later freed by the fire department.
Several other trees were uprooted and struck parked cares. In the district of Hellinghausen, the a church steeple was knocked down.
Videos posted on social media showed a large black funnel approaching a residential area of Lippstadt.
About 200 to 300 firefighters have been deployed there, many of them coming from neighbouring towns and villages.
Large swathes of Germany were under severe weather alerts on Friday evening.
