Lenka Moravcova, a spokeswoman for a rescue service in the northern Czech Republic, said three men drowned in a region on the border with Poland and Germany Saturday.
A fourth victim was found drowned late Saturday. Details were not given.
At least a thousand people had to be evacuated, some from areas below two dams threatened by rising waters.
People in the towns of Chrastava and Frydlant were rescued by police and military helicopters from the roofs of their homes.
Three summer camps for children were evacuated. Meteorologists warned the rains were not expected to stop until Sunday.
Police said floods killed three people in the eastern German state of Saxony.
Authorities in the city of Chemnitz told German news agency DAPD that three bodies were found Saturday in the basement of a flooded building in the town of Neukirchen in Saxony.
Police said a 72-year-old woman, her 74-year-old husband and a 63-year-old man apparently drowned while trying to carry furniture upstairs from the basement. All three lived in the building.
Heavy rains in Poland caused flooding in most of a town of 18,000 people and killed one person.
The floods struck late Friday but worsened on Saturday, leaving three-fourths of the southwestern town of Bogatynia inundated after the Miedzianka River overflowed its banks.
Television news programs broadcast images of men knee-high in water flowing through the town's streets. In some places the water was even higher, almost burying some cars.
Firefighters used boats to evacuate people trapped in homes. Emergency workers from neighboring Germany also mobilized to help the town.
A spokeswoman for local authorities, Dagmara Turek-Samol, told the news agency PAP that one person was killed in the floods.