The main suspect was arrested on Wednesday, with investigators finding chemicals and explosives during a search of his house, the ministry said on Thursday.
The 19-year-old had links with Islamic State, Austria’s public security director Franz Ruf said at a press conference on Thursday.
A second suspect — a 17-year-old — was arrested on Thursday, but he denied being involved in the planned attack, the interior ministry said.
“Thank God a tragedy could be prevented,” Austrian Chancellor Karl Nehammer said Thursday on Austrian TV. The direct terror threat is now cleared, but an “abstract” threat remains, he warned.
Nehammer thanked the Austrian security authorities, but admitted that the crucial hint came from foreign authorities. “Terror can only be fought internationally,” Nehammer added.
The chancellor said he will convene Austria’s National Security Council, which was formed after the 9/11 terror attacks on the United States. The council, which plays an advisory role for the country’s foreign, security and defense policies, is to meet in the coming days.