Search Intensifies and Expands for Missing 7-Year-Old Boy

06/10/2010 at 07:00 PM EDT

Kyron Horman

FBI

After combing through a 2-mile radius where Kyron Horman was last seen, authorities expanded the search for the missing 7-year-old boy, with more than 500 people on the ground, tracking dogs and help from several state and federal agencies.

"We are going to put every effort into this operation," Multnomah County Sheriff Dan Staton told The Early Show Thursday, nearly a week after the second-grader disappeared from his Portland, Ore., elementary school.

Still, officials have become frustrated by how much time has elapsed since the boy was last seen at a school science fair last Friday morning – and worry the window for finding Kyron safely could soon be closing.

Frustrating Search

"The longer we go on with this operation," says Staton, "the greater dangers and risks there are to the child. And that is why this effort is continuing at the level it is currently."

"It's frustrating," Multnomah County Sheriff Capt. Jason Gates said Wednesday, reports The Oregonian. "But we are focused on that mission. We can't concentrate too much on how long it's taking. We have to concentrate on doing our job."

So far, the sheriff's department, with the help of additional searchers from Oregon's 35 other counties, has looked at Skyline Elementary School and the surrounding areas, in addition to conducting door-to-door checks "with every resident in this specific area" and following up on the thousands of tips flooding the tipline, Staton said on Thursday's Today Show. FBI investigators have also interviewed 200 of Kyron's classmates and their parents.

"[Searchers] don't want to stop," says Sgt. Diana Olsen, Multnomah County Sheriff Office's search and rescue coordinator. "They're tired, they're exhausted, but they want to stay with us throughout the full search."

Questions About Parents

And while questions have been raised on why the boy's parents have not spoken publicly – the family issued a statement Wednesday pleading with the community to continue looking for their son – Staton said the parents wanted officials to first "expand their efforts" and have the focus stay on Kyron.

"I'm sure they are going to step forward and reach out [eventually]," said Staton, who adds that the family is has "fully cooperated with us in every effort."