Munich shooting: What we know -- and don't know

(CNN)A gunman opened fire at a Munich McDonald's and then at a shopping mall, killing nine people Friday evening. So far, there are more questions after yet another deadly rampage in Europe.

What happened:

    The gunman started shooting at the McDonald's, then moved across the street to the Olympia shopping mall on Friday.
    Hours after the shooting began, police found the body of the gunman. Based on CCTV and witness statements, they concluded he was the sole gunman. He was found dead close to the shopping center, in a side street.
    The motive remains unclear.

    Weapon:

    The attacker carried a 9 mm Glock 17 pistol that was likely obtained illegally, because the serial number had been scratched off, police said. Germany has strict gun laws and a national firearms registry that requires owners to register their guns with the government. The gunman was found armed with about 300 munition cartridges for the handgun, but there were no explosives in his backpack.

    Victims:

    Authorities said nine people were killed, excluding the gunman, and 27 were injured, 10 with serious injuries. The victims' identities have not been released.
    Most of the victims were teenagers. Three of the victims were 14, two were 15, one was 17 and another 19. A 20-year-old and a 45-year-old were also killed. Three of the victims were female, officials said.
    The victims all were German nationals from the Munich area, officials said. Turkey's Foreign Ministry said three of the victims were also Turkish nationals, naming them as Sevda Dag, born in 1971; Can Leyla, born in 2001; and Selcuk Kilic, according to Turkey's semiofficial Anadolu news agency.
    Another of the victims was also a Greek citizen, Greece's Foreign Ministry said Saturday.
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    Shooter:

    German police have not named the shooter, but they have said he was an 18-year-old student with dual German-Iranian nationality who was born and raised in Munich, and that they have searched his family's apartment. CNN's Atika Shubert interviewed people who live in that building, and they identified the 18-year-old living in that apartment as Ali Sonboly. In a press conference Saturday, German police said the gunman's parents had been taken in for questioning.
    The shooter had received medical treatment for mental issues, a police official said Saturday in a press conference, and investigators are still looking into his mental condition. Authorities said the teen was a mentally troubled man who had extensively researched rampage killings but had no apparent religious or political motives.
    Before Friday's attack, the police had not investigated the teenager. He had been a victim of "bodily harm" in an incident that involved other young people in 2012 and was the victim of theft in 2011, police said on Saturday.
    The parents of the attacker have so far been unable to help police during questioning as they were still in shock over the shooting.
    German police have not named the shooter, but they have said he was an 18-year-old student with dual German-Iranian nationality who was born and raised in Munich. CNN's Atika Shubert interviewed people who live in that building, and they identified the teenager living in that apartment as Ali Sonboly.

    Witnesses:

    Witnesses said the gunman shot at young people, but it's unclear if he was targeting them specifically. He fired into a McDonald's where kids had been eating.
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    One witness said the gunman cursed foreigners while carrying out his attack and was overheard yelling: "You damn foreigners."
    During the rampage, the shooter got into an argument with a witness and their profanity-filled conversation was captured on two camera phones and posted on social media. The shooter was heard saying: "I am German. Are you happy now? I was born here ..." He insulted Turks in the exchange.

    Motive:

    The shooter was a "lone attacker" and there was no indication of ties with ISIS, said Munich Police Chief Hubertus Andrae. Investigators searched his home and found neither reference to religion nor a suicide note.
    But officers found evidence the shooter had been researching shooting rampages, including a book entitled "Rampage in My Mind -- Why Students Kill," according to Robert Heimberger, president of the Bavarian State Criminal Police Office.
    Munich investigators said there were "certain connections" between the Friday attack and the 2011 mass shooting by Anders Breivik in Norway which left 77 people dead exactly five years earlier.
    Investigators pointed to several connections: the date of the shooting was the fifth anniversary of the Norway attack, the age of the victims was similar and the attacker extensively researched mass shootings.