In a brightly lit hall on an industrial estate, rows of empty chairs are arranged in front of a plain wooden lectern.

Hamburg’s Jehovah’s witnesses have cancelled all services following Thursday’s deadly shooting in another meeting hall in the city which claimed seven lives, including that of an unborn child.

The attack took place shortly after worshippers finished their service. Police have told them that they cannot rule out the possibility of a so-called copycat attack, says Michael Tsifidaris, who speaks for the community here.

He’s smartly dressed in a business suit, but looks exhausted. It’s clear that he’s still deeply shaken. Two of his friends were killed in the attack.

He tells us he spent Thursday night with survivors in hospital, and at the police station. But he also comforted relatives as they waited in a hastily arranged emergency centre for news of their loved ones.

“It’s hard to imagine – a group of people are sitting together during an evening in the church, reading the Bible, singing, praying together. Then they spend a couple of minutes together to talk to each other after the meeting, Then, all of a sudden, a scene of love becomes a scene of hate and death.”

The fact that the killer was a former member of the Jehovah’s Witness community here makes the tragedy particularly hard to bear.

There are about 4,000 Jehovah’s Witnesses in and around Hamburg. The community is divided into smaller congregations, each with their own meeting place, known as a Kingdom Hall.

Detectives investigating the mass shooting have said the killer left the Jehovah’s Witnesses on terms which were “not good”.

Mr Tsifidaris says he doesn’t know why the man left, didn’t know him personally, and appears reluctant to talk about him.

Those who leave the Jehovah’s Witnesses are often “disassociated” or cut off by most members of the community; a practice sometimes referred to as “shunning”.

The police have revealed they recently received an anonymous letter, in which the author warned the attacker had a gun, was mentally unstable and harboured anger against religious groups, including the Jehovah’s Witnesses.

“He left the community two years ago and now, all of a sudden, he’s showing up and is acting against all the principles we stand for,” says Mr Tsifidaris.

“What we know is that in the religious context, there is a community he knows, there is a community he was part of, so this is a community he focused his hate on. He knew the premises, he knew the arrangements.”

For now, the community is meeting online. Mr Tsifidaris, who refers to his fellow members as brothers and sisters, speaks often of the comfort to be found in supporting one another. “We pray together, we cry together.”

Uppermost in their thoughts are those who remain seriously injured in hospital. He’s adamant that their treatment is not compromised by a refusal to accept blood transfusions – Jehovah’s Witnesses believe that God forbids this.

They are not yet out of danger, he tells us, but the doctors say there’s a fair chance most will survive.

For now, the focus is on supporting the bereaved and the traumatised. No one, he says, is left alone in their grief.

This attack has left a city in mourning and a community in shock and horror. It will, says Mr Tsifidaris, take years to heal.