A knife-wielding man was shot dead outside the Iranian ambassador's residence in Vienna Sunday night, following an attack on a guard, police said, wrote CNN.

The 26-year-old Austrian, who has not been named, "died on the street from his gunshot wounds" police spokesman Harald Soros said, adding that the guard initially used pepper spray against the assailant.

The attack, which occurred at around 11:35 p.m. local time, began after the man confronted the guard on duty.

"They started a fight because the aggressor was too close and the soldier shot him at least four times with his handgun," said Soros.

The unnamed soldier is in his early 20s and received non-life-threatening injuries to his left upper arm, said Soros. "He is in shock and in the hospital," he said.

The residence, which is guarded around the clock by a soldier from the Austrian army, had security cameras, but it is unknown if the incident was captured on video, said Soros.

It is not known whether Iranian Ambassador Ebadollah Molaei was inside the residence at the time of the attack.

Following the incident, Vienna police stepped up security in other diplomatic missions throughout the city.

"We don't know if this is the only aggressor or if there are other people involved," said Soros.

Earlier this month, four people were stabbed in two separate knife attacks in the Austrian capital.