BERLIN (AP) — Munich on Sunday mourned the victims of the shooting rampage in which nine people were killed, with Germany's president vowing that the country won't give in to fear after a string of violence that also included two attacks claimed by Islamic extremists.

On July 22, an 18-year-old German-Iranian man killed nine people and wounded over 30 others at a McDonald's restaurant and shopping mall in the city. He then killed himself. There was no suggestion that Islamic extremism played any part in the slayings.

"We will probably never find out what really moved him and pushed him to his inhuman actions," President Joachim Gauck said at a memorial event in Bavaria's state parliament.

The rampage in Munich was the deadliest of a string of attacks over a week that rattled Germany — a sequence that also included an ax attack and a bombing in Bavaria that were both claimed by the Islamic State group.

Gauck acknowledged that "the events outstrip our ability to distinguish one act from another — we find it hard to distinguish between whether an act was committed in the name of a religion or an ideology, out of fanaticism, nationalism or racism."

"There is one thing we will not give all those who want to make our home a place of fear and horror, the assailants and gunmen and the terrorists: our submission," he said. "They will not force us to hate like they hate. They will not keep us in the captivity of perpetual fear."

Earlier Sunday, Gauck joined Chancellor Angela Merkel and regional officials at a nondenominational service in the city's Frauenkirche, or Church of Our Lady. That service included an address by a Muslim representative, reflecting the fact that several of the Munich victims were Muslims.

German officials have said the Munich gunman was a withdrawn loner obsessed with playing "killer" video games who had been treated for depression and psychiatric problems. Witnesses said the gunman shouted slurs against foreigners, even though he himself was the German-born son of Iranian asylum-seekers.

The restaurant where most of the victims died was a hangout for youths of immigrant backgrounds, and the dead included victims with Hungarian, Turkish, Greek, and Kosovo Albanian backgrounds and a stateless person.

Bavarian governor Horst Seehofer stressed the importance of fighting all forms of extremism and racism, as well as strengthening security forces.

The rampage in Munich and the attacks elsewhere in Bavaria "have burned themselves into our hearts, and they have also changed the world for us," he said.