A 26-year-old Syrian asylum seeker has turned himself in to police in Germany, saying he was responsible for the Solingen knife attack that left three people dead and eight other injured at a festival marking the city’s 650th anniversary, authorities said early on Sunday.

Officers in Dusseldorf said in a statement that the man “stated that he was responsible for the attack”, adding he has been arrested before.

“This person’s involvement in the crime is currently being intensively investigated,” they said.

Federal prosecutors said they are investigating him on suspicion of murder, attempted murder and membership of a foreign terrorist organisation.

Later on Sunday, the suspect, wearing handcuffs and leg shackles, was taken from the police station in Solingen to make a first appearance before a judge at the Federal Court of Justice in Karlsruhe.

The suspect is a Syrian citizen who had applied for asylum in Germany, police confirmed to the Associated Press.

The dpa news agency reported, without citing a specific source, that his asylum claim had been denied and that he was due to have been deported last year.

On Saturday the Islamic State militant group claimed responsibility for the attack, without providing evidence.

The extremist group said on its news site that the attacker targeted Christians and that as a “soldier of the Islamic State” he carried out the assaults on Friday night “to avenge Muslims in Palestine and everywhere”.

The claim could not immediately be verified.

The attack comes amid debate over immigration ahead of regional elections next Sunday in Germany’s Saxony and Thueringia regions where anti-immigration parties such as the populist Alternative for Germany are expected to do well.

In June, Chancellor Olaf Scholz vowed that the country would start deporting criminals from Afghanistan and Syria again after a knife attack by an Afghan immigrant left one police officer dead and four more people injured.

The attack raised fears that Europe could face another wave of terror attacks. On Saturday, a synagogue in France was targeted in an arson attack. French police said they made an arrest early on Sunday.

Officials earlier said they had arrested a 15-year-old boy on suspicion of knowing about the planned attack and failing to inform authorities, but that he was not the attacker.

Two female witnesses told police they overheard the teenager and an unknown person before the attack speaking about intentions that corresponded to the bloodshed, officials said.

People alerted police shortly after 9.30pm on Friday that a man had attacked several people with a knife in the city’s central square, the Fronhof.

The three people who died were two men aged 67 and 56 and a 56-year-old woman, authorities said.

Police said the attacker appeared to have deliberately aimed for his victims’ throats.

Solingen, a city of about 160,000 residents near the bigger cities of Cologne and Düsseldorf, was holding a Festival of Diversity to celebrate its anniversary.

It began on Friday and was supposed to run until Sunday, with several stages in central streets offering attractions such as live music, cabaret and acrobatics.

The attack took place in the crowd in front of one stage. Hours later, the stage lights were still on as police and forensic investigators looked for clues in the cordoned-off square, but the rest of the festival was cancelled.

The IS militant group declared its caliphate in large parts of Iraq and Syria about a decade ago, but now holds no control over any land and has lost many prominent leaders. The group is mostly out of global news headlines.

Nevertheless, it continues to recruit members and claim responsibility for deadly attacks around the world, including lethal operations in Iran and Russia earlier this year that killed dozens of people.

Its sleeper cells in Syria and Iraq still carry out attacks on government forces in both countries as well as US-backed Syrian fighters.