Investigators are ruling out alcohol, drugs and cellphone use as reasons a van driven by a Colorado sheriff's deputy slammed into a cattle trailer along a rural highway under repair, killing him and five foster and adopted children he and his wife had taken into their home.

The crash Thursday morning on U.S. 287 near Kit Carson also injured seven other children, ages 3 to 17, the couple had taken in.

Of those, one was in serious condition Friday, three were upgraded to fair condition, and one who had been wearing a seat belt was released. The other children's conditions weren't released. The driver of the trailer also is out of the hospital.

Cheyenne County sheriff's deputy Howard Mitchell, 57, had been driving the children from Kit Carson to school in Eads, another small farm town. Only 26 feet of skid marks were found at the accident site, Colorado State Patrol Trooper T.A. Ortiz said.

It's not clear what happened before the crash, but authorities have ruled out cellphone use, alcohol or drugs as factors in the collision.

It happened about 20 minutes after sunrise, and weather conditions were clear with no wind gusts along the north-south highway heavily used by tractor-trailers.

"Of course he had 12 kids in the van, and there will probably be some distraction, but nothing we can prove," Ortiz said. "We can only make our best educated guess as to why. The main factor is probably going to be speed."

The speed limit on the highway is 65 mph but was lower in the construction zone. A final report that would state how fast the van was traveling is not expected for weeks.

Colorado's Department of Human Services was also investigating the crash. Spokeswoman Dee Martinez declined to elaborate, other than to say, "Ultimately, foster kids are under our care and we always work to make sure they are safe and secure."

The collision killed Austyn Atkinson, 11; Tony Mitchell, 10; Tayla Mitchell, 10; Andy Dawson, 13; and Jeremy Franks, 17.

Howard Mitchell and his wife, Melody, operated a state-licensed group home for foster kids in Kit Carson, but their children attended school in Eads.

Gerald Keefe, superintendent of the Kit Carson R-1 School District, said the Mitchells began sending their children to Eads after the Kit Carson school board declined in 2007 to support the Mitchells' application for a group home.

Keefe said group homes can accept children who have had trouble with the law. The Kit Carson board declined to support the application after residents said it would place a strain on the town's 115-student district.

Glenn Smith, superintendent of Eads School District RE-1, said the Mitchells sent their foster and adopted children to the Eads school because they seemed to thrive there. He and Eads High School principal Betsy Bennett said the Mitchells were dedicated to making their children "developing citizens."

Friends were saddened and perplexed about the accident.

"He's a sheriff's deputy and he's an excellent driver," Gary Longwell, a cook at the Trading Post restaurant next to the group home operated by the Mitchells, said of Howard Mitchell. Longwell said Jeremy Franks and two of the injured children worked at the Trading Post.

In Eads, Smith and Bennett described Andy as full of life, always with a smile on his face. Andy was a big University of Oklahoma fan who dreamed of going to school there.

Tony and Tayla Mitchell, Smith said, were full of energy, hugs and smiles. Both were fourth-graders who had been adopted by the Mitchells. Andy Dawson was being adopted, Smith said.

Austyn Atkinson liked middle school and played on the football, basketball, wrestling and track teams.

Jeremy Franks was a sophomore and a football player at Eads' 60-student high school. Smith and Bennett recalled him as a bit ornery and someone with a smirk on his face who always tried to push the limits.

But last month, when a teammate's mother died, Jeremy worked with teachers and staff to design a school card to express condolences.

"It warmed my heart that he would think of another student that he doesn't really know that well. But he knew that it was a hurtful time for the whole community and he wanted to do something about it," Bennett said.

"It was a turning point for him _ when he felt like he was a part of our community and our school."

Eads Mayor Cardon Berry said the town was ready to tend to the children still hospitalized.

"They'll be back and they'll need help and we will help in any way we can," Berry said. "That's just the way it works."