More than a thousand people attended the ceremony at a parking lot near the scene of the murder at the Munich-Solln railway station, including police officers, railway personnel and parents with children. At the same time in the Bavarian capital commuter trains, buses and subway traffic came to a standstill.

Dominik Brunner, a member of the supervisory board of a local company with 600 employees, died after he tried to defend four children against two teenagers. His parents read out a statement at the beginning of the memorial service, thanking people for their condolences.

Speaking at the service, two clergymen appealed for people to show more moral courage.

"This terrible act has prompted feelings of despair, helplessness, anger and grief," said Catholic priest Wolfgang Neidl.

His Protestant counterpart Christian Wendebourg said the businessman's intervention had not been in vain.

"His courage saved the four children...Dominik Brunner had given moral courage a distinctive face," said Wendbourg.

Horst Seehofer wants harsher sentences for young offenders

"Everybody has to ask themselves, should we look the other way? Speaking up and doing something to intervene is necessary - whether it's at the workplace, the school playground, out on the street or in public transport."

Three teenagers are currently being held in police custody. Two male 17 and 18 year-olds are being questioned for murder. A third male, 17 years old, has been detained for suspected predadory extorsion.

German Chancellor Angela Merkel said Brunner was an "example to everyone." But speaking at an election campaign event in the eastern German city of Schwerin, she also warned: "A country where you are free, but at nightfall are afraid to go out on the streets, is not my country."

Earlier on Wednesday members of the Bavarian cabinet posthumously awarded Brunner the Bavarian Order of Merit.

"We want more protection through a greater police presence and more video surveillance," said Seehofer.

There are plans to allow police in uniform or plain clothes to travel free of charge on all trains and buses. Video surveillance is also to be increased on suburban railways.

Twenty people have so far come forward and informed police that they witnessed Sunday's brutal attack. Police have launched an investigation but said there was no proof that any of the witnesses failed to come to Brunner's assistance.

nrt/dpa/epd/AP

Editor: Susan Houlton