Two of the victims were teenagers.
Officers from the Auburn Hills Police Department arrived at the Baymont Hotel at 1294 N. Opdyke Road around 4:36 p.m. to perform a wellness check on an individual female, according to a news release.
They entered the hotel room where they believed she would be and found three dead and an unconscious 20-year-old man.
The Auburn Hills Fire Department rushed him to a hospital, where he was listed in stable condition.
Police said the deceased included a 17-year-old girl and two brothers from Rochester Hills, whose ages were initially given as 18 and 19. The older brother was later said be 20.
The brothers were later identified as Kyler and Caleb Kiessling -- both of whom reportedly struggled with Xanax addiction for years.
"I did everything I was supposed to do to stop this," their adopted mother, Rebecca Kiessling, told Fox 2 in a tearful interview.
The hospitalized man is from Lake Orion.
Investigators told Fox 2 Detroit that they found drugs in the room, and they were being tested. Police said they found no signs of foul play.
Autopsy results were not immediately available, and a toxicology report is not expected to be ready for several weeks.
The state saw a whopping 33 percent increase in drug overdoses between April and May this year, Fox 2 reported, and police were responding to 26 percent more overdose calls between April and June in 2020 compared to 2019.
Within Auburn Hills, police said they had also responded to two other separate overdose incidents in the past 24 hours and that those victims had been revived.
“We would like to urge the public to be incredibly mindful of the substances they utilize as it is extremely heartbreaking to speak to the loved ones and explain that their son or daughter is deceased due to careless drug use,” the department said.