Police in the western city of Koblenz said in a Twitter post on Thursday that four people had died in Ahrweiler County, with around 50 trapped on the roofs of their homes awaiting rescue .
Many of the missing were on the rooftops of at least six houses that were washed away by flooding in the municipality of Schuld, where rainfall caused rivers to overflow, local police said.
Schuld is located in the Eifel, a volcanic region of hills and small valleys southwest of Cologne. The extent of the damage in the area was still unclear after many villages were cut off by floodwaters and landslides that made roads impassable.
Video footage from Bad Neuenahr, about 60 kilometers northwest of Koblenz, showed cars and trucks strewn through the streets and a sport utility vehicle perched on a fence, a road blocked by wreckage and fallen trees as the floodwaters receded.
Authorities declared a state of emergency in the region after days of torrential rains that disrupted rail, road and river transport. Large parts of western and central Germany, as well as neighboring countries, suffered extensive damage.
Police said two men, aged 77 and 82, died after their basements were flooded in the western towns of Kamen and Wuppertal, where authorities warned a roadblock threatened to burst.
A firefighter drowned during rescue work in the western German town of Altena on Wednesday, and another man was missing in the eastern town of Joehstadt after he went missing while that he was trying to protect his property from rising waters, authorities said.
Heavy rains are expected in southwestern Germany on Thursday, with rains continuing until Friday evening, the German weather service warned in a morning report.