The whole apartment block shook and windows in the building shattered. One man in the shop was slightly injured, said police.
The bomb exploded at about 1.30am and witnesses reported seeing one or two people running from the scene. There was considerable water damage to the property’s garage, cellar and store room.
“Both the heating and water pipes which run along the ceiling were burst in the explosion and a lot of water leaked out before we could get a plumber in,” said one of the residents to TT.
The property houses 149 apartments, of which around 90 are on Andra Långgatan.
The resident said that just one window was broken in the explosion, which is thought to have been caused by a hand grenade being thrown into the shop.
He explained that there are several sex shops on the street and despite protests against their presence in the area, nothing like this had ever happened before.
However, police are taking the incident seriously and while the motive was still unclear at lunchtime on Monday, investigators had not ruled out a disagreement between gangs linked to the local sex trade.
Indeed, in the summer there was a shooting incident at a similar shop in the same street.
“It’s especially serious if competing gangs are using weapons and other people end up getting hurt,” said detective Per-Olov Johansson at Gothenburg police.