Three would-be suicide bombers planned to attack a German shopping centre by detonating explosives in rucksacks, according to media reports revealing details of the weekend threat that led to the mall's closure.
Germany's Die Welt newspaper reported on Monday that the suspects had planned to carry out the attack in the city of Essen on Saturday at 4:30 pm (0230 AEST, Sunday).
The mastermind was identified in the report as 24-year-old Imran Reme Q, a man from the nearby city of Oberhausen, who is thought to have travelled to Syria via Turkey in April 2015 to support Islamic State forces in the conflict there.
He had reportedly been on the radar of German authorities as a potentially dangerous person since 2015. Die Welt said that he had recruited several radical Islamists on behalf of the extremist organisation via social media.
Prosecutors in Dusseldorf confirmed that the attack had been planned by a 24-year-old from Oberhausen. They said the suspect had arranged an exact time and location for the bombings.
"This command was given via social media," spokesman Mathias Proyer said, without giving further details.
Authorities ordered the closure of the centre on Saturday, which was followed by armed police encircling the complex.
Two men detained in connection with the incident have since been released, a police spokesman said earlier Monday.
The shopping centre has since reopened. "We are all back at work," centre manager Alexandra Wagner told reporters.
"Life goes on," she added.
German Interior Minister Thomas de Maiziere said security services had alerted police to the possibility of an attack on the Limbecker Platz shopping centre, one of the biggest in Germany's inner cities.
Ralf Jaeger, the interior minister for the North Rhine Westphalia region, stressed that investigations had so far shown no signs "that implementation or preparations had actually begun" for a terrorist attack.
