Austria has closed a mosque and an Islamic association frequented by a man who shot four people dead in a rampage through Vienna on Monday, Integration Minister Susanne Raab said on Friday.
The two sites had contributed to the attacker's radicalisation, she told a news conference.
The 20-year-old convicted jihadist was shot dead by police within minutes of opening fire on bystanders and bars. He was later identified as Kujtim Fejzulai, a native of Vienna.
Police in Germany on Friday searched homes and businesses linked to four people believed to have had ties to the shooter, whom Austrian authorities have described as an "Islamist terrorist".
People from Germany who were being monitored by German intelligence spent time with the attacker in the Austrian capital in the summer, Vienna police chief Gerhard Puerstl told the news conference.
That information, combined with intelligence from Slovakia that the attacker had tried to buy ammunition there, could have led to a "different outcome" and a different assessment of the threat he posed, Puerstl said.