They came in the middle of the night, arriving as the fire was being extinguished at a Plymouth house two weeks ago.
Someone was already rescued from the flames and on his way to the hospital. The quiet scene would now be taken over by workers rarely known to the public.
Since 2005, 19 firefighters have comprised a team that investigates fires in Hennepin County. Their job is to determine cause and origin of the fire, which sometimes can lead to the opening of an arson case.
The head of this group is longtime Golden Valley firefighter David Gustafson, who has also been part of the team before taking the reins. Last month he was named Fire Investigator of the Year by the state's chapter of the International Association of Arson Investigators.
"I want to thank my wife and kids because I'm always leaving for fires at a moment's notice," he said. "And if not for my team and the good work we do, I wouldn't be winning this award."
Gustafson, 50, who also works as an on-call firefighter and investigator for Robbinsdale, led his team on 36 fire calls at homes and businesses in 2016. The causes ran the gamut: five were arson, two from smoking, six were electrical or from unattended outside cooking and seven were from stoves.
The other 16 calls were either to assist at the scene or were undetermined. Many of the fires were in Plymouth or Brooklyn Center, said Gustafson.
The investigators work with law enforcement if necessary. The team is mostly firefighters, but there is also a police officer and attorney on board, said Gustafson.