The Ottawa County Sheriff's Office deputies said the investigation began in the morning when they were assisting the Grand Haven Fire Department with a house fire.
The initial calls for service came in between 8:30 a.m. and 9 a.m. about the smell of smoke in the area.
No fire was immediately found, according to deputies.
Around 11:40 a.m., deputies and fire personnel returned to the area when they received calls about white smoke showing from a residence in the 14900-block of Riverside Trail.
Fire crews worked to put out the flames and check the residence for any victims.
Deputies said multiple people were found dead inside the home, and OCSO detectives began an investigation into the incident.
OCSO said eight people died in the fire, including two adults and six children. In a press conference on Friday evening, the sheriff's office said the children ranged in ages from 5 years old to 15 years old. They also confirmed some of the deceased suffered gunshot wounds.
Michigan State Police arson investigators responded to the scene.
The sheriff's office said there appears to be no threat to the public.
The investigation is ongoing.