A couple from Cloquet were found dead from suspected carbon monoxide poisoning in their camper over the weekend.
Pamela and Richard Smith, 65 and 67, respectively, were found in the vehicle in Brookston, about 16 miles northwest of Cloquet, at 7:15 a.m. on Saturday, according to the St. Louis County Sheriff's Office.
They were declared dead at the scene after resuscitation efforts proved unsuccessful.
The sheriff's office said the cause of the carbon monoxide appears to have been a generator that had been placed in an unvented storage cabinet below the camper's living space.
The camper was equipped with a CO detector, which was working and sounding during the incident.
Although investigators believe CO poisoning led to their deaths, this will be confirmed at a later stage by the Midwest Medical Examiner.
The odorless and colorless gas is deadly, with the Centers for Disease Control saying it is particularly dangerous to older people who suffer from chronic heart disease, anemia or breathing problems.
CO deaths in Minnesota
The latest figures from the Minnesota Department of Health relating to CO poisoning are from 2015, when 12 people in the state died.
That was down compared to 2014, when there were 14 deaths, and 2013 when there were 18.
People aged 65 and older accounted for the highest proportion of the deaths.
The gas is found in fumes produced when you burn fuel, from cars, trucks, generator engines, stoves, lanterns, grills, fireplaces, gas ranges and furnaces. You can read more about the symptoms here.