Three children were in fair condition at a Chattanooga hospital Monday, two weeks after a school bus crash killed six of their classmates.

On Nov. 21, 37 students from Woodmore Elementary School boarded bus No. 366 to head home. But within a mile of the school, the driver lost control of the bus and crashed while speeding down a narrow road, according to police. Six children died from their injuries and 12 others admitted to the hospital following the crash, which the National Transportation Safety Board is investigating.

The bus driver, Johnthony K. Walker, was arrested the night of the crash and charged with multiple counts of vehicular homicide. Walker, 24, remained late Monday in the Hamilton County, Tenn., jail, where he was being held on $107,500 bond.

After receiving several complaints about Walker's dangerous driving and behavior, the Hamilton County school district twice informed the bus company, the district said. Three days later, Walker, was still behind the wheel and speeding down residential road — a road not on his route — when he lost control of the bus and crashed, according to police.

Walker declined to speak with NTSB investigators following the crash, the agency said. The final investigative report could take more than a year to be released, the NTSB said.