German Chancellor Angela Merkel condemned the "poison" of racism Thursday after a shooter with apparent far-right beliefs killed nine people at a shisha bar and a cafe in the city of Hanau, sending shockwaves through the nation.

All nine victims, aged between 21 and 44, had a "migrant background," although some were German citizens, chief federal prosecutor Peter Frank said.

The suspect, 43-year-old German Tobias R, was found dead at his home alongside his 72-year-old mother in what appeared to be a murder-suicide.

Prosecutor Frank said evidence, including video and a 24-page "manifesto" found on the suspect's website, "shows a very deeply racist attitude".

The killing spree fuelled alarm about Germany's emboldened far-right, coming after a neo-Nazi attack at a synagogue and the murder of a pro-migrant politician last year.

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Speaking in Berlin, Ms Merkel said: "Racism is a poison, hatred is a poison and this poison exists in our society and it is already to blame for far too many crimes."

Among the dead at the two bars were "several victims of Kurdish origin", the Kon-Med association of Kurds in Germany said in a statement.

A Bosnian and a Bulgarian were also among those killed.

Six others were injured, one critically.

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Tears and anger

The rampage started at around 10pm Wednesday at the Midnight shisha bar in central Hanau, some 20 kilometres east of Frankfurt.

The gunman reportedly rang the doorbell and then shot at people in the smoking section, mass-market daily Bild said.

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He fled the scene by car before opening fire at the Arena Bar & Cafe.

After a massive manhunt, the suspect was found dead at his flat, along with his mother. Both were killed by gunshot. The suspect's father was unharmed and is not being treated as a suspect.

Prosecutor Frank said investigators were trying to determine if the suspect had accomplices or contacts in Germany or abroad who would have known about the attack plans.

Relatives and friends of the victims gathered at the Arena bar on Thursday, an AFP reporter said, tearfully embracing one another.

"I couldn't be any more upset," said Inge Bank, 82, who lives near the bar.

"We have to nip it in the bud if the Nazi party is coming back," Ms Bank said, adding that she had lived through World War II.

German President Frank-Walter Steinmeier placed a wreath of white flowers outside the Arena bar on Thursday evening before joining residents in a vigil for the victims.

Similar solidarity rallies were due to be held in Berlin, Frankfurt and dozens of other cities across Germany.

Frankfurt's Eintracht football team said it would hold a minute's silence ahead of its Europa League match against RB Salzburg.

The Berlinale film festival said it would open with a moment's silence for Hanau.