Terrified parents in Portland, Ore., have begun keeping their children out of the elementary school where second-grader Kyron Horman vanished after an early-morning science fair.
Nearly 40 students failed to report to Skyline Elementary School Tuesday, five days after Kyron was last seen walking toward his classroom. He never made it.
School Principal Benjamin Keefer said he understands the concern.
"My children go to this school, so it's something that, for me, hits really close to home," he said. "But we're all trying to stay strong and make it through these difficult times."
Multnomah County Sheriff's Capt. Jason Gates said today that hundreds of search and rescue members from all over Oregon have been called into Portland.
"We are looking for a living Kyron Horman," he said, adding that tips continue to pour in, mostly from Oregon and Washington state.
Intensive search efforts have been hampered by the cold, wet weather, frustrating authorities and increasing the concern for Horman in case he's exposed to the weather.
The FBI and National Guard were brought in over the weekend and authorities are now calling the search a criminal investigation even though they said earlier this week that they had no evidence Kyron had been kidnapped.
Former FBI agent and ABC News consultant Brad Garrett told "Good Morning America" today that while the investigation initially didn't appear to include any viable leads, that may have changed.
"I think they're thinking … that someone did do something to this child," he said.
Horman's parents have not yet spoken publicly, but are expected to release a statement later today.
There has been no trace of the 7-year-old boy who proudly showed off his project on frogs at the school science fair. He was last seen by his step-mother walking toward his classroom, 150 feet away.
Gates said a source at the school saw him around 9 a.m. Friday, but declined to provide details. The school does not have video cameras.
The disappearance has been hard on local authorities.
"Kyron, we're going to bring you home buddy," Gates said Monday, struggling to hold back tears. "Nothing is more important to your family and friends."
Gates said authorities have received 1,200 tips, but are continuing to seek out anyone who was anywhere near Skyline Elementary School in Portland Friday morning.
More than two-thirds of the school's population, about 300 children in grades K-8, showed up voluntarily Sunday to be interviewed by police.
Among their questions were about Kyron's likes and dislikes, his hobbies and his friends.
Investigators also stood in the street near the school this week around the same time Kyron disappeared Friday, questioning drivers who may pass the school as part of their normal routes.
Gina Zimmerman, president of the school PTA, told the Portland Oregonian that her 8-year-old daughter Madi has been a classmate of Kyron's for three years.
"He's not the type of child who would just go out of school and go searching or wandering around," Zimmerman said. "He's just a timid, sweet boy.
"Everybody's just worried and in shock that this could happen in our little school where everybody knows everybody," she said.
Anyone with information regarding Kyron Horman's whereabouts is asked to call the Multnomah County Sheriff's Office tip line at 503 261-2847.