Police responded to a call at 3:45 p.m. to reports that several people were unconscious. Authorities said six adults and an infant were found at the North Range Crossings Apartments on East 104th Avenue, along with “illicit narcotics.”

A four-month-old infant and an adult were found alive in the apartment and were both transported to a nearby hospital, police said.

“While they thought that most of them were unconscious, one of the parties was awake and was transported by medical,” Commerce City Police Chief Clint Nichols said.

“Unfortunately, the other five people inside the apartment were deceased,” Nichols added, noting that the five adults found dead were three women and two males.

“There does not appear to be any blunt trauma or any violent incident of any nature,” he said.

Nichols said “illicit narcotics” were found after a search of the apartment. He noted that a hazardous gas test conducted by the local fire department came back negative.

“There was some substance inside. We don’t know exactly what anything is as of yet,” he said. “Again, there were some substances that could be described as illicit narcotics, but again, for me to speculate on that would be improper. I just don’t know.”

He added the substance was still being tested.

Nichols said police would obtain a search warrant to launch a probe into the incident, and that the property would be “cleanly swept” by a hazardous materials team to ensure the safety of investigators.

He added that none of the six adults made the phone call to emergency services. It isn’t clear who contacted the police department.

“If it is going to be illicit drugs, they were very, very bad,” Nichols said. “If it was drugs, no one was able to get to a phone and call 911 for a medical emergency. It happened pretty quickly—speculation on my part.”

The surviving adult was conscious and able to speak to police, Nichols said. The infant also appeared to be in good health and had a checkup at hospital.

Nichols said it wasn’t clear at this stage whether the infant’s parents were among the deceased.

“I hope the parents were not in there, but I’ve been doing this long enough… it would probably be safe to suggest the parents probably were inside and so for the infant, that’s going to be a long time without parents.”

The identities of the victims have not yet been released by authorities. An investigation into the incident is underway.

Newsweek has contacted the Commerce City Police Department for comment.