BERLIN — Austrian authorities searched the Vienna home Monday of a man who attacked a guard outside the Iranian ambassador's residence and was then fatally shot, but said they still have no information on his motives.

Police said the guard, a 23-year-old Austrian soldier, first tried to deter the assailant in Sunday night's incident with pepper spray. After the attacker — a 26-year-old Austrian — stabbed him, he fired several shots. The assailant died at the scene.

The soldier sustained cuts to his right arm but was protected from more serious injuries by his stab-proof jacket.

The local branch of the domestic intelligence and anti-terror agency was investigating the case. Police said the assailant's apartment in Vienna was searched on Monday, but there was no immediate sign of evidence that would point to a motive.

Investigators seized a computer and a cellphone, and said that it might take several days to finish combing through the data.