A 16-year-old Afghan friend of the attacker who opened fire near Olympia-Einkaufszentrum shopping mall in Moosach district of Munich in Germany has been arrested.
The assailant had killed nine people in the shooting rampage before committing suicide.
The 16-year-old Afghan, arrested at his home in Munich, is being investigated because he is suspected to have acted as a possible accomplice, local police said as quoted by Xinhua.
Investigators also need to figure out to which extent the arrested person is responsible for a Facebook call for a meeting in a cinema complex near the Munich central train station.
On early Sunday evening, more than thousands of residents spontaneously took part in different memorial services.
The shooter, an 18-year-old German-Iranian teenager, started planning the attack one year ago. He had been living in Munich for two years, CNN reported.
The motive for the shootings was unclear and a state of emergency was declared in Munich.