Emergency workers and police gather at the scene following a deadly shooting in Hamburg, Germany. Reuters

A gunman stormed a service at his former Jehovah’s Witness hall in Germany, killing six people before taking his own life after police arrived, authorities in the port city of Hamburg said Friday.

Police gave no motive for Thursday night’s attack. But they acknowledged recently receiving an anonymous tip that claimed the man identified as the shooter showed anger toward Jehovah's Witnesses and might be psychologically unfit to own a gun.

The first emergency calls were made around 2015 GMT on Thursday after shots rang out at the building in the city's northern district of Gross Borstel, a police spokesman at the scene said.

Police tweeted that "several people were seriously injured, some even fatally" in the incident.

"At the moment there is no reliable information on the motive of the crime," police said, urging people not to speculate.

An alarm for "extreme danger" in the area had been sounded using a catastrophe warning app, but Germany's Federal Office for Civil Protection lifted it shortly after 3am local time.

Munich Police tweeted early on Friday: "The police measures in the surrounding area are gradually being discontinued. Investigations into the background of the crime are continuing."

The port city's mayor, Peter Tschentscher, expressed shock at the shooting on Twitter.

Sending his sympathies to the victims' families, he said emergency services were doing their utmost to clarify the situation.

Bible study group 

In the nondescript, three-storey building, police said an event had been taking place on Thursday evening.

Jehovah's Witnesses had gathered for a weekly Bible study meeting, according to local daily Hamburger Abendblatt.

There are about 175,000 people in Germany, including 3,800 in Hamburg, who are Jehovah's Witnesses, a US Christian movement set up in the late 19th century that preaches non-violence and is known for door-to-door evangelism.

The first officers at the scene found several lifeless bodies and seriously wounded people, police said.

Hamburger Abendblatt reported that 17 unhurt people, who had been at the event, were being attended to by the fire brigade.

Officers heard a shot in the "upper part of the building" before finding a body in the area where it rang out, police said.

"We have no indications of a perpetrator on the run," said the police spokesman.

Instead, officers have "indications that a perpetrator may have been in the building and may be even among the dead."

The spokesman added that the person uncovered in the upper part of the building was "possibly" the perpetrator.

"We have found a lifeless person in a community centre in [Gross Borstel] which we assume could be a perpetrator," Munich Police tweeted early on Friday morning.

"According to the current state of affairs, we assume that there is one perpetrator," police said in a separate tweet.

Hit by attacks 

Germany has been rocked by several attacks in recent years by militants.

Among the deadliest committed by extremists was a truck rampage at a Berlin Christmas market in December 2016 that killed 12 people.

The Tunisian attacker, a failed asylum seeker, was a supporter of the Daesh group.

Europe's most populous nation remains a target for militant groups in particular because of its participation in anti-Daesh coalition in Iraq and Syria.

Germany has also been hit by several far-right assaults in recent years, sparking accusations that the government was not doing enough to stamp out neo-Nazi violence.

In February 2020, a far-right extremist shot dead 10 people and wounded five others in the central German city of Hanau.

And in 2019, two people were killed after a neo-Nazi tried to storm a synagogue in Halle on the Jewish holiday of Yom Kippur.

Agence-France Presse