Munich - Police on Saturday were hunting for clues to explain why an 18-year-old German-Iranian man opened fire in a crowded Munich shopping mall and fast-food restaurant, killing nine people and wounding 16 others before killing himself.The attack in the Bavarian capital sparked a massive security operation as authorities - already on edge after the recent attacks in Wuerzburg and Nice, France - received witness reports of multiple shooters carrying rifles shortly before 16:00GMT. Six hours later police declared a "cautious all clear," saying the suspect was among the 10 dead and that he had likely acted alone.Peter Beck, a Munich police spokesperson, said officers were still collecting evidence at the scene of the crime on Saturday morning."With regard to the suspect we have to examine everything, but we don't know yet what triggered the crime," said Beck. He declined to confirm reports by German daily Bild that officers had raided a home in the city's Marxvorstadt district about 2km from the mall and were interviewing the suspect's father, citing "ongoing police operations."Beck said the number of people receiving hospital treatment stood at 16, three of whom were seriously wounded. Security restrictions in the city have been lifted and public transport is operating as normal, Beck said.German Chancellor Angela Merkel was due to chair a meeting of her government's security cabinet on Saturday.No evidenceAbout 2 300 police from across Germany and neighbouring Austria were scrambled in response to the attack, which happened less than a week after a 17-year-old Afghan asylum-seeker wounded five people in an ax-and-knife rampage that started on a regional train near the Bavarian city of Wuerzburg. The Islamic State group claimed responsibility for the train attack, but authorities have said the teen - who was shot and killed by police - likely acted alone.Munich police chief Hubertus Andrae told a news conference early on Saturday that the shooting suspect was a dual citizen who had lived in the city for some time and whose motive was still "fully unclear." He said it was too early to label the attack an act of terrorism, though police had used the term earlier to describe the nature of their operation, which included calling in the elite GSG9 special operations force."The question of terrorism or a rampage is tied to motive and we don't know the motive," Andrae said.Andrae said the suspect's body was found about 2 1/2 hours after the attack, which started at a McDonald's across the street from the mall. The body was determined to be the shooter based on witness statements and closed circuit television footage of the attack, he said.The man, whose name wasn't released, was not previously known to police and there was no evidence of any links to terrorist organisations, Andrae said.A cell-phone video posted online showed the suspect dressed in black standing on a rooftop parking area of the mall yelling back and forth with the person filming, saying at one point "I'm German" and eventually firing shots. Andrae said police believe the video is genuine.Witnesses had reported seeing three men with firearms near the Olympia Einkaufszentrum mall, but Andrae said two other people who fled the area were investigated but had "nothing to do with the incident."The police chief said the nine fatalities included young people; children were among the 16 wounded, three of whom were in critical condition.At least three of the victims appeared to be of Kosovo-Albanian origin, according to Facebook posts from family members. Their identities couldn't immediately be officially confirmedMunich has large communities of people who fled the Balkan wars in the 1990s.