Vienna terror attack
Vienna terror attackReuters

Slovakian intelligence told their Austrian counterparts in July that the man who shot and killed four people in a terror attack in Vienna this week had tried to buy ammunition there and mistakes were apparently made in dealing with that information, Austrian authorities conceded Wednesday, according to The Associated Press.

The suspect, identified as 20-year-old Kujtim Fejzulai, had a previous conviction for trying to join the Islamic State (ISIS) group in Syria and had been given early release in December.

In addition to killing the two men and two women, he also wounded more than 20 people in a nine-minute attack before being killed by police on Monday night.

Bars and cafes were crowded with people enjoying warm weather and a last evening out before the establishments were due to close under new coronavirus restrictions.

The attacker was armed with an automatic rifle, a handgun and a machete, and wore a fake explosives vest.

Austrian officials say that Fejzulai, a dual citizen of Austria and North Macedonia, hoodwinked the justice system's deradicalization program after his release. Interior Minister Karl Nehammer said Wednesday that other things appeared to have gone wrong, according to AP.

Slovak intelligence informed Austria that Fejzulai was trying to buy ammunition, and “something apparently went wrong with the communication in the next steps,” Nehammer said.

He added that he would propose that an independent panel to be set up to examine “where things happened that shouldn't have happened.”

In Slovakia, police said they received information during the summer about “suspected persons from Austria” trying to buy ammunition.

“They failed to make the purchase,” they said. “We immediately sent the information to our Austrian colleagues.”

Austrian public security director Franz Ruf said Austrian intelligence officials received the information and asked questions of their Slovak counterparts but it's unclear “whether the process went optimally.”

ISIS on Tuesday claimed responsibility for the deadly shooting attack in Vienna, though it did not elaborate on the attacker’s ties to the group.