On the way to school, two girls were attacked and seriously injured by a man in Illerkirchberg (Alb-Donau-Kreis).
They were taken to a hospital on Monday, police said.
The investigators did not initially give any further details about the girls and their injuries.
The alleged perpetrator is said to have fled to a neighboring apartment building.
The police found three people in the house.
"We assume that the perpetrator is among them," said a police spokesman.
The operation with the help of a special task force was completed, there was no danger to the population.