A memorial service is being held in the western German city of Duisburg one week after the Love Parade dance festival ended in tragedy.
Twenty-one people died and more than 500 were injured during a mass panic and crush at the event.
As a mark of respect, flags across Germany are flying at half-mast.
Prosecutors have launched a criminal investigation to determine whether negligent manslaughter was involved in the deaths of so many young people.
Chancellor Angela Merkel has broken off her summer holiday to attend the memorial service at the Salvator Church in Duisburg, along with friends and relatives of those killed at the Love Parade festival, staged a week ago.
Local pastor Martin Weinberg told the congregation: "We want to show our solidarity with those who are in shock, who are full of grief and worry, who are searching for answers and also with those who blame themselves for what happened".
Rescue workers who had helped to look after the victims at the festival site lit a candle for each person who died.
While the church can only seat around 600 people, hundreds more are watching the service on big television screens at other churches and a football stadium in the city, says the BBC's Tristana Moore, in Berlin.
Angelika Schick, who visited the Love Parade with her two daughters, has been watching the service in the stadium of local team HSV Duisburg. "I hope this service will help me to find peace", she told German public broadcaster ARD.
Before the service, churchbells across Duisburg and neigbouring cities rang in memory of those who died.
All week long people have been laying flowers and lighting candles at the exit to the tunnel where the deadly stampede took place.
As German prosecutors continue their inquiry into the disaster, police investigators have accused the Love Parade organisers of failing to control the huge crowds which led to a bottleneck at the tunnel, the only entrance to the festival grounds.
Feelings have been running high and angry residents have staged rallies demanding the resignation of Duisburg's mayor, who has been blamed for ignoring safety warnings in the run-up to the festival, our correspondent says.
Adolf Sauerland said he would not attend the memorial service because he feared his presence would hurt the feelings of victims' relatives. The mayor has been placed under police protection after receiving a number of death threats.
