According to Upper Austrian police, a 19-year-old man from Mondsee prepared a 'spray candle' firework from ingredients, including salt and powered sugar, which he had bought from a hardware store.
When the Mondsee man attended a party, he brought the firework with him, and left it unattended at the door of the house.
The Linz man attending the same party left the house briefly at 11:20 p.m. for a smoke break, and is believed to have picked up the improvised explosive mixture while holding a cigarette.
The resulting blast severely damaged his left hand, as well as causing burn injuries to his thighs and face. Police have been unable to question him as his injuries are so serious. Investigations continued on Thursday, and are expected to last a few days.