A fire on Sunday destroyed historic industrial buildings and left four people injured in Arbon, a town near Lake Constance in the canton of Thurgau.

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The blaze destroyed three halls and seriously damaged two others. The property used to be owned by Saurer, a company that once built trucks and buses there.

A total of 39 companies had operations in the complex after it was sold by Saurer in March to HRS Investment for 35 million francs, the Blick newspaper reported.

The conflagration is believed to have started on Sunday afternoon in a building used by a recycling company, before spreading to other buildings.

The cause of the fire is not known while an investigation continues, Thurgau police said.

Police said 360 firefighters from Arbon and nine other cities, including Romanshorn and Saint Gallen, fought the flames.

Ambulances took four firefighters to hospital for injuries, while 10 others were treated as outpatients for exposure to heat.

Heavy smoke poured from the site for several hours after the fire was extinguished but police said this posed no danger to residents or animals in the neighbourhood.

The police department’s forensic service is investigating the reason for the blaze.

However, they face a challenge inspecting the site because of structures that are in danger of collapsing, police said.

Investigators are seeking information from witnesses who may be able to provide clues about what happened.