The bus assistant and a child remained in serious condition at University Hospital in Lexington, Ky., as of Tuesday after a school bus crash Monday in Carroll County that killed two 3-year-old Head Start students, state police said.

The two children who were killed were identified as Ryder Deitz, the son of Ron and Kelly Deitz of Sanders, and Caroline Elizabeth Tuttle, the daughter of Chris and Stacy Tuttle of Sanders. Obituaries for both children are on Page A7.

Two other children were in stable condition in the intensive-care unit at Kosair Children's Hospital today, while a third child is listed in good condition.

One of the children injured in the crash was released Tuesday, Kosair spokesman Steve Menaugh said. The child initially had been in the intensive-care unit, then the medical surgery floor.

The school bus driver was taken to Carroll County Memorial Hospital and was released Monday.

Two children who had been released at the scene of the accident were taken to Kosair Children's Hospital as a precaution. They were checked out and released to parents Monday.

Nine Carroll County Head Start students were riding the bus home when it crashed. The accident happened Monday around 4:30 p.m. in the 3200 block of Boone Road. The Carroll County School District school bus left the road for an unknown reason, turned over on its side and struck a tree, which caused the roof to collapse and the chassis to detach, state police said.

The bus, which was not a full-sized school bus, had seat belts, and state police believe the seat belts were in use by all occupants at the time of the crash, a release said.

Counselors were available at all of the Carroll County Schools on Tuesday, and the Carroll County Child Development Center, the Head Start and Early Head Start Programs were not in session because of the accident. Flags were ordered to half-staff across Carroll County.

The Kentucky State Police is leading an investigation into the accident. An accident reconstruction team is looking for any mechanical problems or other factors that might have caused the bus to crash. Another reconstruction team is investigating factors at the crash site that could have caused the crash.