After receiving several complaints about a bus driver’s dangerous driving and behavior, the school district in Hamilton County, Tenn., twice informed the bus company, the district said in a written statement Tuesday.

“Transportation Director Ben Coulter spoke in person about the written complaints with Durham School Services personnel on Wednesday November 16, 2016 and again on Friday November 18, 2016,” the district statement said.

Three days later, the same driver, Johnthony K. Walker, was still behind the wheel and speeding down a narrow, residential road in Chattanooga — a road not on his route — when he lost control of the bus and crashed, according to police. The Nov. 21 crash killed six children and injured 30 other students from Woodmore Elementary School, including two who remained in critical condition Tuesday afternoon.

Walker, 24, was arrested the night of the crash and charged with multiple counts of vehicular homicide.

Durham School Services, which operates the district’s buses, declined to discuss Tuesday whether it took any disciplinary action against Walker after learning about complaints against the driver.

Walker appeared in court briefly Tuesday morning, but his preliminary hearing was postponed until Dec. 15. He was being held in the Hamilton County jail late Tuesday on $107,500 bond.

Investigators are going over the path of the bus and looking into how fast the driver may have been going.