The incident occurred in the western harbour district of Malmö on Saturday evening. Rescue services were quickly on the scene and six people were taken to hospital, one with serious but not life threatening injuries.
“Suddenly everything began swinging and within a minute the houseboat had gone completely down into the water,” one witness who was on the boat told local paper Sydsvenskan.
The reason for the boat’s collapse remains unclear but police have not ruled out foul play. Technicians have already been on site examining the scene with a report expected to be submitted to the owners and the insurance company next week.
“Nobody is suspected for a crime yet,” said Skåne police’s Nils Norling.
A total of 42 people were on the houseboat but nobody was reported missing. Nine fire trucks and members of the local coast guard were involved in the rescue operation.
Witnesses described chaotic scenes of people crawling out of the windows of the houseboat while emergency services helped others out of the canal.
Some local businesses also provided blankets and hot drinks for those that had been rescued.
“It was like the Titanic. People were climbing up the sides,” another witness told the paper.
“It could have ended very badly. They were lucky it happened when it did in daylight and before people had time to get drunk.”
Incident commander Paul Bjurehag told the TT news agency the accident may have been caused by a design flaw in the houseboat’s construction.
“A house is not supposed to collapse in this way,” he said.
He added that two identical houseboats beside the sunken one should be inspected as precaution.