37-year-old electrician Holger S. stabbed his son and daughter – Lisa (10) and Tim (9) - before jumping from the bridge in eastern Hesse with them, reports Bild.de.
The three fell 95 metres, and were found by pedestrians.
The family came from Mecklenburg-Western Pomerania, reports Tagesspiegel.
The father had been separated from the children's mother for a few years, but at the time of the tragedy, he was looking after the children with their mother's consent.
Friends described him as a loving father, who just a few weeks ago decorated the house for his child's birthday.
"They were a completely normal family," one neighbour told Bild.de.
But according to prosecution services in Gießen, he had been worried that he would lose the children in a custody battle with their mother.
According to police, the man stabbed both of his children in the torso whilst on the bridge, before jumping to his death with them.
"The tragedy has got under everyone's skin, even the experienced officers," a police spokesperson said.