California Highway Patrol officers investigate the scene of a charter bus crash on northbound Highway 99 between Atwater and Livingston, Calif., Tuesday, Aug. 2, 2016. A charter bus veered off a central California freeway before dawn Tuesday and struck a pole that sliced the vehicle nearly in half, killing multiple people and sending at least five others to hospitals, authorities said. (AP Photo/Scott Smith)
The Associated Press
FRESNO, Calif. (AP) - Investigators are collecting medical records and lining up interviews with relatives of a bus driver in a crash that killed four passengers in Central California when the vehicle hit a highway sign post that tore through its frame, officials said Thursday.
The team wants to know how much rest Mario David Vasquez, 57, of Los Angeles got in the days leading up the crash, Robert Accetta of the National Transportation Safety Board told reporters in a Modesto news conference.
"We will look at all aspects of this collision," Accetta said. "Is fatigue an issue? Was there a mechanical issue with the bus?"
The bus manufactured in 1998 veered off a San Joaquin Valley highway before dawn Tuesday and struck an exit sign post. It was carrying 27 people.
Investigators have not been able to interview the driver who remains hospitalized and unconscious, Accetta said.
Federal and CHP investigators are also checking the bus company's records and making detailed inspections of the damaged bus, the highway sign and the roadway to determine what caused the crash.
The bus was too old to have a computer that records the engine, telling investigators if the bus exceeded the speed limit of 65 mph. Accetta says his team will have to rely on witnesses and the spread of debris to determine speed.
They'll also try to discover if the drier was texting, talking on a cell phone or distracted by an electronic device. "We'll be looking at that as well," Accetta said.
Carin Sarkis, of Doctors Medical Center in Modesto, said two of the most seriously injured have been released from the hospital, leaving four still in their care.
California Highway Patrol officers investigate the scene of a charter bus crash on northbound Highway 99 between Atwater and Livingston, Calif., Tuesday, Aug. 2, 2016. A charter bus veered off a central California freeway before dawn Tuesday and struck a pole that sliced the vehicle nearly in half, killing five people and sending at least five others to hospitals, authorities said. (AP Photo/Scott Smith)
The Associated Press
California Highway Patrol officers investigate the scene of a charter bus crash on northbound Highway 99 between Atwater and Livingston, Calif., Tuesday, Aug. 2, 2016. A charter bus veered off a central California freeway before dawn Tuesday and struck a pole that sliced the vehicle nearly in half, killing five people and sending at least five others to hospitals, authorities said. (AP Photo/Scott Smith)
The Associated Press
Rescue crews respond to the scene of a charter bus crash on northbound Highway 99 between Atwater and Livingston, Calif., Tuesday, Aug. 2, 2016. The bus veered off the central California freeway before dawn Tuesday and struck a pole that sliced the vehicle nearly in half, authorities said. (Andrew Kuhn/Merced Sun-Star via AP)
The Associated Press
Rescue crews respond to the scene of a charter bus crash on northbound Highway 99 between Atwater and Livingston, Calif., Tuesday, Aug. 2, 2016. A charter bus veered off a central California freeway before dawn Tuesday and struck a pole that sliced the vehicle nearly in half, authorities said. (Andrew Kuhn/Merced Sun-Star via AP)
The Associated Press