Sheriff: Kyron "Endangered" Missing Child

The mystery continues in Oregon.

How did a 7-year-old boy disappear after arriving safely at school?

It's been nearly a week since Kyron Horman vanished from his elementary school. "Early Show" National Correspondent Hattie Kauffman reported Thursday morning hundreds of experts will join forces with investigators from 22 agencies in a desperate search. But officials admit the clock is ticking.

Pictures: Kyron Horman Missing

Police Capt. Jason Gates, of Multnomah County Sheriff's Office, said, "We are moving forward under the premise that we are looking for a living Kyron Horman and that's their focus."

FBI agents have stopped cars, others searched the rugged, densely covered hillsides around the school.

Kyron's stepmother says she snapped a picture of him at the school science fair Friday, and then left him in the building. He never made it to his first class. He was reported missing seven hours later when he wasn't on the school bus.

His parents are talking to police, but not the press. Wednesday they said through a spokesperson that they want to keep the focus on their son.

Capt. Mike Shults, the family's spokesperson, told reporters, "I stand here in front of you today because I carry the burden of sadness and pain they're experiencing."

Investigators have questioned 90 percent of the students who attend this school -- and their parents -- to see if any of them saw Kyron on Friday.

Tanner Pumala, a student at Kyron's school, said, "I'm feeling really sad, and I am hoping that Kyron my best friend will come back."

Jinnet Powell, a parent, said, "This is something that you never want to happen to anyone."

Sheriff Dan Staton of Multnomah County and Sheriff Tim Evinger of Klamath County appeared on "The Early Show" Thursday from Portland, Ore., to discuss their search.

Staton said investigators are classifying Kyron an "endangered missing child."

"We cannot put specifics on this," he said. "We have to look at every possibility."

However, he said the longer the search goes on, "the greater dangers and risks there are for the child."

Staton said the search has expanded to include 532 people on the ground. He said searchers from the FBI, the community and county agencies, will start at "Ground Zero" -- where Kyron was last seen -- and work out from there.

Staton said this next, ramped-up phase of the search also includes canine and air support. He added searchers will be expanding the operation further out from where they'd been focusing.

Staton said in the past seven days, police have also covered every home in the area where Kyron went missing. He confirmed interviews have been conducted with many families and children that go to the school with Kyron.