A spokeswoman for the Hamburg prosecutor's office said on Saturday that a custody warrant has been issued for the man being held on suspicion of carrying out the stabbing attack in Hamburg.

The 26-year-old failed asylum seeker is currently being held on suspicion of one count of murder as well as five counts of attempted murder, spokeswoman Nana Frombach said. The accused has not produced any information about his motives or the sequence of events at the Edeka supermarket on Friday and provided "no evidence" of being mentally unfit to stand trial.

The suspect has no identity papers other than a birth certificate showing he was born in the United Arab Emirates.

Praise for bystanders

German authorities on Saturday praised bystanders who subdued a man fleeing after he attacked shoppers at a supermarket in Hamburg with a knife. They potentially saved lives after a rampage that left one person dead and several injured, police said.

Chancellor Angela Merkel praised the police and civilians who showed "civil courage and bravery" in standing up to the knife-wielding attacker.

A video made minutes after the attack showed several civilians getting up from a nearby cafe and confronting the knifeman with chairs and stools until police arrived at the scene to arrest him.

Hamburg Interior Minister Andy Grote called Friday's civil arrest outside the supermarket in the city-state's Barmbek district "very courageous and very determined."

Mayor Scholz and Hamburg Interior Minister Andy Grote lay flowers at the site of the attack

'Heroes of Hamburg'

German media are dubbing the men who went after the attacker with chairs - reportedly mostly Muslims of Arab and Turkish descent - as the "Heroes of Hamburg."

The attacker was a rejected asylum seeker, who earlier on Friday had inquired at a city office for foreigners about whether deportation papers had arrived.

The attacker had become radicalized but also suffered psychological problems, Grote said.

"It remains unclear which was the overriding element," he said, adding there were no indications of a terror network behind the attack.

The suspect had no criminal record in Germany, with the exception of an alleged shoplifting incident in April that was dropped as a "slight" matter, according to Jörg Fröhlich from the Hamburg state prosecutors' office.

The man is likely to be charged with murder and five counts of attempted murder, Fröhlich said.

Police on Saturday said they had searched a refugee shelter in the Hamburg district of Langenhorn, where the suspect was believed to have been staying. Nothing was found, police said.

Purchased bread, grabbed knife

Lead investigating police officer Kathrin Henning told journalists the assailant had first purchased bread at a branch of the German supermarket chain Edeka. He briefly boarded a bus, but got off, and returned to the supermarket's entrance.

He ripped a 20-centimeter (8-inch) knife from its wrapping and "brutally" attacked two men, including a 50-year-old man who died, Henning said.

Among those injured was a 19-year-old and two people on bicycles, she added.

A 50-year-old woman and four men aged between 19 and 64 were also all injured, as well as a 35-year-old Turkish man who was part of a group that chased and overpowered the suspect.

The attacker, who was arrested by police, was said to have shouted "Allahu Akbar" (God is the Greatest) during the rampage.

German Interior Minister Thomas de Maiziere cautioned against jumping to conclusions about the motive.

"The jihadist ideology could be used as a justification for action that may actually be motivated by other reason," he said, adding that "the real motives could perhaps lie in the personality of the perpetrator."

Call to speed up deportations

Hamburg Mayor Olaf Scholz (seen laying flowers in top photo) said the attack had been motivated by "hate."

It appeared that the suspect was facing deportation but this had not proceeded because he lacked identification papers, Scholz said.

"I am furious that the offender is apparently someone who has claimed protection with us in Germany and then directed his hate against us," the mayor added.

"These criminals want to poison our free society with fear, but they will not succeed," said Scholz.

Speaking of a "malicious attack," Scholz added that the case showed "all the more urgently that these legal and practical barriers to deportation must be removed."

Police arrested the man after he was subdued by members of the public

Drug and mental issues?

The website of the Spiegel news magazine said the individual was named Ahmad A., who had arrived in Germany seeking asylum and had contact with the Islamist scene, as well as a history of drug use and mental health problems.

Germany has been on high alert over the possibility of another Islamist attack since Tunisian Anis Amri drove a truck into a crowd at a Berlin Christmas market in December last year, killing 12 people and injuring 48 others.

Read more: Berlin launches probe into Christmas market attack

Like the alleged Hamburg attacker, Amri was a failed asylum seeker who could not be deported for lack of documents.

The similarity between the cases risks reopening wounds over Chancellor Angela Merkel's decision to allow more than a million migrants into Germany since 2015.