Austrian police made 14 arrests after a gunman murdered four people in the heart of Vienna on Monday.
The man, described as a 20-year-old Islamist terrorist who had been freed from jail last December, was shot dead by police as he fired on passers-by.
Security has been tight in the Austrian capital as police launched a manhunt for any further attackers.
But authorities now believe the gunman may have acted alone.
Austrian Chancellor Sebastian Kurz said the four who died were an elderly woman, an elderly man, a young man and a waitress. Another 22 people were wounded.
One of the women who died was German, Germany’s foreign minister said.
Interior Minister Karl Nehammer said there was no indication that a second assailant had been involved, though that could no be ruled out. Police were still assessing some 20,000 mobile phone videos of what happened.
The Islamic State (IS) group claimed in a video on its online propaganda channel that it was behind the attacks, without providing any evidence.
The gunman began his assault at 8:00pm local time and continued until he was shot dead at 8:09pm.
The attack came hours before Austria imposed new national restrictions to try to stem rising cases of coronavirus. Many people were enjoying having a drink or eating out before a midnight curfew.
Police identified a total of six crime scenes in the area. A three day national mourning was announced, with flags flying at half mast.