A leading candidate in Cologne's mayoral race has been stabbed in what officials are saying is a politically motivated attack.
Henriette Reker - an independent candidate supported by Chancellor Angela Merkel's CDU party - was wounded in the neck in the attack on Saturday.
Local police said Ms Reker, 58, was "stable, but not out of the woods".
Officials said the attacker may have targeted her because of her role in looking after refugees in the city.
Police have arrested a 44-year-old German national and Cologne resident. He told officials he attacked Ms Reker "because of anti-foreigner motives," according to senior police investigator Norbert Wagner.
The suspect appeared to have acted alone and had no police record, Mr Wagner added.
Ralf Jager, a regional interior minister, said: "The first signs speak for a politically motivated act."
The attacker will undergo a psychiatric examination to establish whether that was his primary motive or whether he had a health problem.
Another woman was seriously wounded and three people suffered minor injuries as they tried to overwhelm the man.
City officials said the election would go ahead as planned. Ms Reker has been the head of Cologne's social affairs and integration department since 2010.
Ms Merkel has come under fire from some in Germany over the large numbers of refugees and migrants being allowed into the country.
Germany has said it expects 800,000 people to seek asylum this year, but a leaked report suggested the number could be as high as 1.5 million.