Preliminary autopsy results showed that all seven people found dead inside a duplex apartment in this northeast Missouri town suffered carbon monoxide poisoning, Adair County Coroner Brian Noe said Tuesday.

"It does not appear to be any trauma — no injuries, no signs of struggle, anything like that were found," Noe said.

Police said they wouldn't comment until later Tuesday. Noe said toxicology results wouldn't be available for four to six weeks. Those results will help determine if other factors contributed to the deaths of the five young adults and two children.

As a result, Noe said he wasn't yet willing to say if the deaths were accidental.

"Anytime you have seven people in that type of circumstance you look at every avenue," Noe said.

The bodies were discovered Sunday afternoon by 15-year-old Heather Glaspie and two of her friends. Glaspie was the baby sitter for the two children and became worried when she couldn't reach their mother, Maranda McDermott, 23, the tenant of the duplex that sits a few blocks from the Truman State University campus.

At a candlelight vigil Monday night, about three dozen relatives and friends of the victims had already decided carbon monoxide was to blame. They just didn't understand how it could happen.

"I'm going to miss my grandbabies," said Grayling Ramsey, the grandfather of the two youngest victims. "You can't question God why he did this. He did it for a reason. But it's hard."

Police didn't identify the victims, but relatives said McDermott, 23, died, along with her son Adam McDermott Jr. and daughter Melina McDermott. Adam turned 1 Thursday. Melina would have been 2 on Dec. 30.

"We just celebrated both of their birthdays last week," Ramsey said.

Relatives identified two of the other victims as Jeremy Liner, 19, and Reginald Washington, 21. The other victims were a 21-year-old man and 21-year-old woman. All were from Kirksville. None were students at Truman State.

A woman living in the building's other apartment was evaluated at a hospital but was OK.

The children had a 4-year-old sister who wasn't home at the time, and who was now under the care of her grandparents, Ramsey and his wife, Lisa Lewis.

Carbon monoxide can kill silently, its victims simply going to sleep and never waking up. Still, neighbors and people around town wondered how someone among the seven couldn't have noticed that something was amiss.

On Monday, Police Chief Jim Hughes confirmed a reading on a fire department sensor indicated a high level of carbon monoxide. Investigators were consulting with the maker of the carbon monoxide detector to get a better understanding of what the reading meant.

"It's a very critical element of our investigation," Hughes said.

The home heating system was functioning properly and was not the source of any problem, Hughes said. A van parked in the garage was taken to a crime lab, but Hughes would not say if the van had been running inside the enclosed garage. The lab was also looking at a second van parked on the driveway.

Glaspie often watched the children for McDermott, who worked two jobs at different nursing homes. The two corresponded by text message at 3 a.m. Sunday.

At 7 a.m., Glaspie tried to contact McDermott, but couldn't. Worried, she and two friends went to the home in the afternoon. Once inside, they knew something was wrong.

"It had a funny smell," Glaspie said. "The carbon monoxide alarm was going off."

Glaspie's friend, Lisa Brake, said they saw McDermott on the floor of her bedroom and the other adults in the living room. The children were tucked into bed.

"We thought they were sleeping," Brake said.

But no one would wake up. Then they checked on the children.

"Adam was purple," Glaspie said. "We were yelling at them to get up, but no one moved."

Ramsey said he and Lewis had taken the 4-year-old sibling to St. Louis for Christmas shopping Sunday. They were on their way back to Kirksville when they got a telephone call from Glaspie, telling them what had happened.

Speaking of the 4-year-old, Lewis said the child's father died a year ago, "which leaves her with just us. I don't know what I'm going to do when she asks me what happened to them. But I will do my best."

Kirksville, a town of 17,000 residents, is about 30 miles south of the Iowa border and 165 miles northwest of St. Louis.