ORLAND —

Even as the wreckage was being cleared, investigators from the National Transportation Safety Board and the CHP special accident team were collecting evidence on site.

They bring with them some hi-tech expertise.

“The investigators will use sophisticated surveying and mapping equipment and 3D mapping equipment in order to fully reconstruct the sequence of events that caused the collision,” said Lt. Scott Fredrick of the CHP.

What we know is that a FedEx truck heading south on Interstate-5 crossed the median through Oleander bushes and struck the charter bus head on.

“We don’t know if the FedEx driver had fallen asleep, whether he experienced some mechanical failure with his vehicle, or whether there was a separate collision on the southbound side which caused him to lose control,” Fredrick said.

A key to the investigations may be whether a white sedan hit collided with the truck.

There were two occupants in the sedan that was struck and they both sustained minor to moderate injuries,” said CHP Lt. Commander Bruce Carpenter.

They of course will be interviewed as part of the investigation.

The 30 surviving passengers of the bus will need to be interviewed as well. Not all of them are in a condition to speak right now.

The CHP says not to expect a definitive answer to what caused the deadly crash for at least six months, and it could take as long as a year.