German president Horst Koehler led thousands of Germans at an emotional remembrance service in Winnenden for the victims of a school massacre that left 16 dead.
Tim Kretschmer, 17, shot dead 12 people at his former school in Winnenden on 11 March. He killed three more outside before killing himself when he was cornered by police.
"Such acts lead us to the limit of comprehension," Koehler told the service in a packed church, his voice shaking with emotion. "But so long as we can stick with and help each other, we are not helpless."
"The whole of Germany is grieving with you," he added, visibly struggling to hold back tears. "You are not alone."
Schoolmates of the victims lit candles bearing their names at the service, which was broadcast for thousands to see at a nearby stadium, and also carried live on national television.
The families of five schoolgirls killed in the attack wrote to Koehler, Chancellor Angela Merkel and their state premier calling for curbs on young people's access to weapons, a ban on violent video games and less violence on television.
Investigators have said they found violent video games on Kretschmer's computer.
"We must all look at what we can do better in the future, what lessons we can draw from this," Koehler said in his address.
He said it was up to not only the state but also individuals to question what films they watched or games they played, and what example they set for their children and fellow citizens.