In the capital of German state of North Rhine-Westphalia, Dusseldorf, three people were found dead under a garden shed. The rest three deaths were reported from other German cities of Essen, Cologne and Krefeld, Xinhua reported.
According to local media, squalls, lightning and hail damaged many homes and cars in the west European country.
"We must expect that the total damage amounts to a double-digit million amount," said Ralf Jaeger, interior minister of the North Rhine-Westphalia state.
Meanwhile, the storms in North Rhine-Westphalia also led to cancellations and delays of the trains, even the airport Dusseldorf had to cease operations for about an hour on Monday evening, due to the strong wind gusts of up to 150 km per hour.
Overall, the police in the state had come to help for about 5,000 times, according to the German national control centre.
Moreover, Germany will still be stricken by thunderstorms in the coming days, as the forecasters expect thunderstorms in southeast of the country on Wednesday and in the south on Thursday.