Durham School Services, the company Hamilton County Schools contracts with for busing services, has had 346 crashes in the past two years, according to federal figures.
Three fatalities resulted from those crashes and 142 of the crashes caused injuries. During the past two years the company had 53 incidents involving "unsafe driving violations," federal numbers show.
The Illinois-based company is one of the largest suppliers of school bus services, operates about 13,700 vehicles across the country and has nearly as many drivers, according to the Federal Motor Carrier Safety Administration. Durham was awarded a "satisfactory" safety rating from the agency in July 2015.
After the fatal crash yesterday that killed at least five Woodmore Elementary School students, at least 10 National Transportation Safety Board employees are investigating the incident.
A typical NTSB investigation takes between 12 and 18 months to complete, according to Keith Holloway, a spokesman for NTSB.
"With any NTSB investigation, the goal from a safety perspective is to determine not just what happened but why it happened and possibly make safety recommendations to prevent it from happening again," Holloway said.
"Investigators will examine the vehicle involved, collect maintenance records, medical records of the driver, conduct interviews with those involved and other witnesses."
In a written statement, Durham said it's devastated by yesterday's fatal bus crash.
"We are working with the Chattanooga Police Department and Hamilton County School District to investigate," David Duke, CEO of Durham School Services said. "We also have additional team members arriving in Chattanooga today to provide support."
Durham is offering to provide counseling to students and families of Hamilton County, along with its employees.
The Illinois-based company declined to answer any questions about the crash or the driver's history.