Two men died at a farmhouse in Peralada, Girona, after inhaling carbon monoxide from a generator installed in a garage where there was no ventilation.
The two fatalities are the 64-year-old owner of the farm and a 52-year-old man who helped with farm work.
Police found the lifeless bodies in the garage, a few metres from the generator. The generator was still running.
The main theory is that the two men started up the generator and then, being in a small space with no ventilation, were overcome by carbon monoxide fumes.