BERLIN >> A Palestinian man who allegedly stabbed one person to death and wounded six others in Hamburg was known to authorities as a suspected Islamic radical but was also considered psychologically unstable, German officials said today.

The suspect, a 26-year-old who had no identity papers other than a birth certificate showing he was born in the United Arab Emirates, was quickly overwhelmed by passers-by and arrested after Friday’s attack at a supermarket in Hamburg’s Barmbek district.

He was not named by authorities in keeping with Germany privacy laws.

The man’s motive remained unclear Saturday but he is believed to have acted alone and there are no indications he had links to any network, Hamburg state interior minister Andy Grote said.

A judge issued a formal arrest warrant Saturday that keeps the suspect in custody pending possible charges of murder and five counts of attempted murder, Hamburg prosecutors’ spokeswoman Nana Frombach told the dpa news agency.

She said officials next week will consider whether federal prosecutors, who handle terrorism cases in Germany, should take over the case.

Police said the suspect grabbed a kitchen knife with a 20-centimeter (nearly 8-inch) blade from a supermarket shelf on Friday afternoon and stabbed three men, one of them fatally. He then left the supermarket and hurt another three people outside, not all of them with the knife. Passers-by then pursued and overwhelmed him and he was arrested by police.

An additional person was slightly hurt when she fell in the tumult, police said.

Grote said none of the wounded was being treated for life-threatening injuries Saturday, although some were seriously hurt. He and Hamburg Mayor Olaf Scholz toured the site of the attack, talked to witnesses and met with one of the hospitalized victims.

The suspect arrived in Germany in March 2015 after stops in Spain, Sweden and Norway. His asylum request was rejected late last year and authorities were trying to secure new Palestinian papers to deport him — a process in which they said he had cooperated.

Officials said he was on their radar as a suspected Islamic radical but not as a “jihadist.”

A friend had tipped authorities off to changes in the man, telling them that he stopped drinking alcohol and started talking about the Quran, said Torsten Voss, head of the Hamburg branch of Germany’s domestic intelligence agency.

Officials interviewed the man and came away with the impression he was a “destabilized personality” but not an immediate danger, Voss said.

“We evaluated him rather as someone who was psychologically unstable than had clear Islamic extremist motivations,” Voss said at a news conference.

A search of the man’s room at an asylum-seekers’ center turned up no weapons.

The suspect hasn’t yet talked about Friday’s attack, prosecutor Joerg Froehlich said, although he has indicated that he acted alone.