Taylor Swift concert terror plot suspect sought to kill self and 'as many people as possible,' officials say

The main suspect, 19, had materials used to make explosives, investigators said.

The main suspect, a 19-year-old Austrian citizen, fully confessed to attack plans during an interrogation, according to Omar Haijawi-Pirchner, head of Austria's Directorate of State Security and Intelligence.

The suspect was "clearly radicalized in the direction of the Islamic State" and allegedly intended to kill himself and "as many people as possible" outside the concert venue using knives and homemade explosives, Haijawi-Pirchner said during a press conference Thursday in Vienna.

The 19-year-old, who was from the Austrian town of Ternitz and had North Macedonian roots, had been preparing for the attack since late July and drastically changed his appearance, according to Franz Ruf, the public security director at Austria's Ministry of Interior. He researched bomb-making techniques and uploaded to the internet an oath of allegiance to the current leader of the Islamic State, Haijawi-Pirchner said.

A second suspect -- a 17-year-old Austrian citizen – was arrested in Vienna on Wednesday afternoon. A 15-year-old Turkish citizen was also detained and questioned, according to Haijawi-Pirchner. No further suspects are being sought, Ruf said.

Each of the two suspects was known to police and both were said to have been involved in the direct preparation of the foiled attack, according to Haijawi-Pirchner. Most of the plans and preparations were made at the 19-year-old's home, Ruf said.

A 15-year-old, who was interrogated, had been asked by the main suspect about ignition mechanisms, Haijawi-Pirchner said.

The 17-year-old suspect, who has Turkish-Croatian roots, was employed a few days ago at a facility company providing services at the concert venue and would have been working there, according to Haijawi-Pirchner. It was discovered during the investigation that he was on the grounds of Vienna's Ernst Happel Stadium, where three Taylor Swift concerts were to be held,

ABC News' Aaron Katersky, Will Gretsky, Emily Shapiro, Josh Margolin and Luke Barr contributed to this report.