Authorities overseeing one of the largest search-and-rescue operations in state history said Monday that a missing 7-year-old Portland boy likely didn't simply walk away from school when he disappeared 11 days ago.

PORTLAND — Authorities overseeing one of the largest search-and-rescue operations in state history said Monday that a missing 7-year-old Portland boy likely didn't simply walk away from school when he disappeared 11 days ago.

Multnomah County Sheriff's Capt. Jason Gates said the massive search for Kyron Horman has been scaled back, but it continues as a criminal investigation. Kyron went missing June 4 after a science fair at his elementary school.

"The process is not over," Gates said. "We as an investigative team are resolved to bring Kyron home. This will not become a cold case for us."

The teams searching for Kyron had included more than 1,300 volunteers from across the state, as well as from southern Washington state and northern California. Most of those teams were sent home Sunday.

A more limited search team from Multnomah County will canvass Skyline Elementary School again this week. That's where Kyron was reportedly last seen.

"It's not a search-and-rescue operation anymore," Gates said.

He added that parents in the area shouldn't take extra precautions with their children. Authorities have said since the earliest days of the investigation that they believe Kyron's disappearance was an isolated case.

"There is no reason to believe that the kids are in any danger here," Gates said. The sheriff's office has offered a $25,000 reward for information that leads to the boy.

Despite the announcement that the disappearance is now being investigated as a criminal case, the sheriff's office has refused to say whether they have identified any suspects or have any theories about Kyron's disappearance.

Gates reiterated Monday that the release of any details could compromise the investigation.

Kyron's family, including his mother, stepmother, stepfather and father, have made two public appearances. In the first one Friday, they pleaded for Kyron's return but would not take questions. They re-emerged Sunday at a press conference but did not release a statement. Capt. Monte Reiser of the sheriff's office has said that authorities can charge a suspect without finding Kyron.

The search-and-rescue teams spent 10 days combing the two-mile radius around the school, as well as "individual areas" which Gates again declined to identify Monday.

Gates said the sheriff's office will establish a "war room" in their downtown Portland building which will be dedicated to the search and investigation.