Police in the German city of Munich have asked members of the public to submit any videos, photos or audio recordings from Friday's mass shooting.
Nine people were killed and 16 wounded, three of them critically, at a shopping mall by a lone gunman who later shot himself dead nearby, police say.
No motive for the German-Iranian man's actions has yet been established.
The attack is the third on civilians in western Europe in eight days, following the violence in Nice and Wuerzburg.
Three of the victims were from Kosovo. The father of one of them, 21-year-old Dijamant Zabergja, was photographed holding a photo of his son near the mall on Saturday. The other two were young women.
Police will give an update on their investigation later on Saturday. They are asking people to upload any recordings that could help them to a special account.
Munich, capital of the southern German state of Bavaria, was rocked by the attack on Friday evening.
The mayor of Munich, Dieter Reiter, thanked police in a statement (in German), saying, "These are difficult times for Munich. I am impressed by the readiness of Munich residents to help, and their solidarity. Our city stands together."
Interior Minister Thomas de Maiziere has ordered flags to be flown at half-mast across Germany in mourning.
Chancellor Angela Merkel has delayed a holiday in the Alps to chair a meeting of the national security council later on Saturday.
People could be seen laying flowers and lighting candles outside the Olympia shopping mall on Saturday.
First reports of the shooting came in just before 18:00 (16:00 GMT) on Friday.
Witnesses say the attacker opened fire on members of the public in Hanauer Street before moving on to the mall.
A grainy video appears to show a man firing a gun outside a McDonald's fast-food restaurant as people flee.
Another video shows the gunman walking around alone on a flat roof before again opening fire. He can be heard shouting at the person filming, saying at one point, "I'm German".
Witness Luan Zequiri, who was in the shopping centre, told German broadcaster N-TV the attacker had been wearing military-style boots and a backpack.
"I looked in his direction and he shot two people on the stairs," he said.
Mr Zequiri said he hid in a shop, but when he left, he saw dead and wounded people on the ground.
The name of the gunman, who was 18, was not given. He had lived in Munich for more than two years, police said.
His body was found about 1km (half a mile) from the mall.
Munich police chief Hubertus Andrae told reporters overnight that the killer had not been known to police and he had no known links to militant groups.
The attack came just four days after a teenage Afghan asylum seeker stabbed and injured five people on a train in Bavaria before being shot dead by police.
Claiming the attack, the self-styled Islamic State (IS) group later released a video showing the 17-year-old brandishing a knife and making threats.
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