Police in the eastern German town of Halberstadt began an investigation against a 43-year-old Bulgarian after an explosion in his home. According to the investigators, he caused the blast on Sunday to Monday morning.
The man, who also has German citizenship, has suffered heavily and is in medically induced coma.
Investigators have found chemicals for explosives -separate chemical elements, the supply of which is legal.
Because of the explosion, 650 people had to be evacuated and spend the night on Monday in temporary accommodation.
