“The world has gone mad,” says one mourner holding a bouquet of white roses and approaching the entrance of the brick building, cordoned off by police.

The body bags are carefully placed in hearses before being driven away and the man with the bouquet leaves with his flowers still in hand.

“It really upsets me,” says Tatjana Popczy, who lives just 200 metres (yards) from the centre where a former member of the Jehovah’s Witnesses burst into a service at around 9:00 pm (2000 GMT) on Thursday, killing six people.

There is nothing remarkable about the building, located on a busy thoroughfare between a petrol station and auto repair shops. The group’s logo, a small square with “JW” in white letters on a blue background, is affixed to the facade.

“It doesn’t matter where it is, it’s awful,” says Popczy as a clutch of people come to pay their respects and place flowers in front of a sign displaying the centre’s opening hours. “I cannot understand how you could do such a thing.”

Across the road, residents in a large apartment complex describe the Jehovah’s Witnesses opposite as “discreet”.

Bernd Miebach, 66, found police swarming his neighbourhood after he returned late Thursday from an evening out. Officers questioned his adult son after he filmed part of the assault on his phone from the family apartment, about 50 metres from the religious centre.

“On the video you can see that someone broke a window, you can hear shots fired and see that someone broke in,” the elder Miebach says.

READ ALSO: UPDATE: Gunman kills six people at Jehovah’s Witness centre in Hamburg

The suspect killed himself after police arrived.

“I heard the gunshots. I recognised them immediately because I have lived in a war zone,” says a middle-aged woman who lives close by. “It lasted for several minutes. Shots and then a pause and then shots again and another pause,” the woman told AFP on condition of anonymity.

“The police arrived really quickly, maybe four or five minutes after the shots,” says Anetta, another resident who followed the events from her balcony. “People are dead. I’m lost for words, it’s a catastrophe,” she tells AFP.

Germany has about 175,000 Jehovah’s Witnesses, including 3,800 in Hamburg, where the group has multiple centres, according to their website.