Sept. 30, 2012 -- There are few clues this morning in the search for two missing Tennessee children following a house fire that killed their grandparents last week.
Tennessee officials put out a statewide Amber Alert on Friday for 9-year old Chloie Leverette and her 7-year-old brother, Gage Daniel.
A fire destroyed the Unionville, Tenn., home where the children lived with their grandparents Molli and Leon McClaran on Sept. 23. They were killed in the blaze and at first everyone thought the kids were killed, too. The cause of the fire is still unknown.
"I don't know what to think. I don't know what to think," Christopher Daniel, Gage's father, told The Associated Press Saturday. "They don't think that they burned up in the fire, the way I took it they don't."
After cadaver-sniffing dogs combed through the debris, only physical evidence remained of the grandparents, not the children.
"If we just had ashes, their little bodies, you know, but we don't have anything," said the children's aunt, Mary Lamb, Molli McClaran's sister.
Several fire experts were called in to try to find some trace of the missing bodies in the ash, and investigators used infrared cameras attached to helicopters to scour the scene, but nothing turned up.
"The fact that we don't have sufficient evidence from fire investigators right now to positively conclude that they died in this fire, makes us want to make sure that they are not somewhere else," Tennessee Bureau of Investigation spokeswoman Kristin Helm said earlier.
According to Helm, the TBI has no direct evidence that the children, who were reportedly last seen near the home around 6:30 Sunday night, about three hours before the fire began, are victims of foul play.
"It's extremely frustrating for investigators, particularly when you have children of tender years like these two ... unless they are with someone who has no intention of harming them, you're very concerned that they've been in harm's way," former FBI Agent and ABC News consultant Brad Garrett said.
Police are questioning everyone who knew the kids, including their parents, but investigators said they have no suspects and aren't even sure they have a crime.
"Their mother has been spoken to, she does not have the children," Helm told ABC News.
Between 2006 and 2010, the Tennessee Department of Children's Services investigated the children's mother and Daniel's father, The Associated Press reported. The department is sharing that information with investigators, spokesman Brandon Gee said.
"The key in this case is the origin of the fire," said Garrett. "Is it an accident or is it intentional?"
ABC News' Clayton Sandell and The Associated Press contributed to this report.