Chancellor Angela Merkel on Tuesday condemned violent far-right protests that degenerated into attacks against foreign-looking people, saying "hate in the streets" has no place in Germany.
After the fatal stabbing of a German man, 35, allegedly by a Syrian and an Iraqi, thousands of protesters marched in the eastern city of Chemnitz for two straight days, some chasing down people they believed were immigrants.
Police reported assaults by far-right extremists against at least three foreigners on Sunday, while investigations were opened in 10 cases of the protesters performing the illegal Hitler salute.
At least 20 people were injured on Monday as pyrotechnics and other objects were hurled by both far-right demonstrators as well as anti-fascist counter-protesters in the city.
"What we have seen is something which has no place in a constitutional democracy," Merkel told journalists.
"We have video recordings of (people) hunting down others, of unruly assemblies, and hate in the streets, and that has nothing to do with our constitutional state."
Interior Minister Horst Seehofer said federal police were ready to provide back-up for overwhelmed officers in Saxony state, where Chemnitz is located.
But there was little sign of the marches spreading further Tuesday, with a right-wing demonstration in the state capital Dresden attracting just 50 people, according to regional newspaper Saechsische Zeitung.
The ugly scenes of mostly white men, many of them extremist football hooligans, hurling abuse at people they deemed to be foreigners, have deeply alarmed Germany.
"Of course history is not repeating itself, but that a far-right mob is on a rampage in the middle of Germany and the authorities are overwhelmed, is reminiscent of the situation during the Weimar Republic," said Spiegel Online.
The Weimar years were marked by the formation of paramilitary groups, such as the Sturmabteilung or SA, which eventually helped the Nazis to power.
Josef Schuster, who chairs the Central Council of Jews in Germany, also voiced his alarm, saying it is "now the duty of citizens to counter the far-right mob".
Anetta Kahane of the anti-racism Amadeu Antonio Foundation told news channel NTV that, while people have the right to demonstrate, "what happened in Chemnitz went beyond that -- it was incitement to hatred and the propagation of pogrom sentiment."
The circumstances that led to the death of the German man remain unclear, but the far-right quickly mobilised Sunday as word spread online that the key suspects were foreigners.
Saxony's interior minister Roland Woeller said hooligans from across Germany, including as far as the western states of North Rhine-Westphalia and Lower Saxony, had travelled to Chemnitz for the marches.
State premier Michael Kretschmer warned that a false claim that the man was stabbed while defending a woman was circulating online, as he urged the population to seek credible news sources.
He also stressed that the nationalities of the suspects were "absolutely no reason to cast general suspicion on all foreign-born citizens".
'Nothing more dangerous'
Saxony state, where Chemnitz is located and which is the birthplace of the Islamophobic PEGIDA street movement, has repeatedly come under intense scrutiny as a hotbed for hate crimes.
The state is at the heart of misgivings over Germany's decision to welcome more than a million asylum seekers since 2015, many from war-torn Syria and Iraq.
Railing against the newcomers, the far-right AfD party has made significant gains in Saxony and is poised, according to the latest polls, to become the second biggest party in its regional elections next year.
Critics warned that the authorities have for years failed to take the far-right threat seriously.
"The state can never allow our streets to be overrun by far-right mobs," said Bild daily, adding that at the same time, Berlin needs to promptly deport criminal foreigners.
"For too long, nothing has been done. That's why confidence in the state is crumbling. That's why racists like in Chemnitz think they can do what they want. Nothing could be more dangerous for our country."
Frankfurter Allgemeine Zeitung noted that "where such hunting down of foreigners is possible, the rule of law has abdicated," while Die Welt daily warned that "the rule of law and police now face a test".
"There cannot be a zone of violence, there is no such thing as partial security," said Welt.