A 16-year-old friend of the gunman who killed nine people in the German city of Munich on Friday has been arrested by police.

Investigators say the Afghan teenager is suspected of knowing about David Ali Sonboly's planned attack and failing to report it.

Munich police added that the friend may have played a role in a Facebook post which invited people to a meeting place in the city centre.

German media is reporting the arrested boy had gone to the police himself in the aftermath of the shooting.

Munich Gunman's Specific Target

On Sunday evening, an estimated 1,500 people gathered at the shopping centre where the attack unfolded to light candles and lay floral tributes in memory of the victims, the majority of whom were teenagers.


Earlier, detectives confirmed Sonboly had bought the gun used in his rampage on the dark web, and had been plotting the shooting for more than a year.

:: Germany Rocked By Week Of Bloody Violence

Thirty-five people were injured in the shooting spree, with 10 severely injured and three in a critical condition.

None of those who were injured or killed were classmates of the 18-year-old gunman.

Police have described Sonboly as a deranged Iranian-German who was fixated with mass killings but not inspired by Islamist militancy.

Image: Police at the Olympia-Einkaufszentrum shopping centre in the northern part of Munich Image: The authorities initially urged people to avoid the area Image: Officers secure the area inside the shopping centre. Continue for more images Image: Police walk inside a subway station Image: Officers guard with guns as other officers escort people from inside the shopping centre Image: Police walk into the shopping centre in Munich Image: Police secure the area near Stachus square Image: Police secure the area of a subway station Image: Police officers escort people from inside the shopping centre /

In the run-up to his attack, he had visited the site of a school shooting in Winnenden to take photographs, and he was also an avid player of first-person shoot-em-up video games.

Bavarian prosecutor Thomas Steinkraus-Koch has confirmed Sonboly feared contact with others and had previously been treated for mental health problems at a psychiatric inpatient in 2015.

Police have been probing claims that the killer felt bullied by his peers and that he may have been inspired by Norwegian mass murderer Anders Breivik, who killed 77 people exactly five years before the Munich shootings.

Just weeks before the shooting, Sonboly had warned a 14-year-old girl living in his apartment block: "I will kill you all."