Three dead were recovered from a building fire in Kraichtal, north-east of Karlsruhe.
Among them are "probably children," reported the police in Baden-Württemberg after initial findings.
In addition, a man with severe burn injuries was flown to a clinic by helicopter.
The fire broke out in a family home around noon on Tuesday.
It was initially unclear whether there were other people in the house.
Investigators have not released any information about the cause of the fire.