California Highway Patrol officials have completed their investigation of the interior of the bus where they discovered one body.
The bus and two other vehicles involved in the crash are being towed from the crash site.
One adult female was confirmed dead at Redlands Community Hospital, according to a hospital spokeswoman.
The bus and two other vehicles in the crash will be removed from the scene and investigated for mechanical issues.
Numerous 9-1-1 calls began to flood the CHP and the San Bernardino County fire dispatch center around 6:30 p.m., reporting that a large bus had overturned and was blocking Highway 38 near the Mill Creek Ranger Station east of Mentone.
The bus driver, who has been identified as 52-year-old Norberto Perez of San Ysidro, a district in San Diego, on Sunday picked up 38 passengers in Tijuana.
The bus crashed into a Saturn before veering off the road and overturning.
The bus hit a boulder on the side of the road which set the bus upright before crashing into a Ford pickup truck hauling a trailer traveling northbound, said CHP Officer Leon Lopez.
Six bus passengers were thrown from the vehicle.
Authorities continued working Monday, Feb. 4, 2013, to clear the scene of Sunday's fatal bus crash on Highway 38 north of Yucaipa that left at least eight people dead and 20 wounded.
The bus company, Scapadas Magicas, has been in business for about 20 years and has turn around trips to Disneyland, Magic Mountain, Big Bear, and more.
Federal records show the bus company has a history of maintenance issues.
The bus driver has been interviewed at a nearby hospital.
"Speed seems to be a factor but we don't know what caused the bus to speed down the mountain road," Mario Lopez said.
Victims were transported to nearby hospitals including Arrowhead Regional Medical Center in Colton, Loma Linda University Medical Center and Children's Hospital in Loma Linda and Redlands Community Hospital.
Six patients were sent to Redlands Community Hospital for treatment.
One crash victim was transported to Loma Linda University Medical Center for further care.
An adult female was pronounced dead at Redlands Community Hospital, said Nikyah Thomas-Pfeiffer, marketing manager for the hospital.
Two female victims were transferred to Arrowhead Regional Medical Center in Colton where they are listed in critical condition in the hospital's Intensive Care Unit.
Two adult males were also transferred to Arrowhead from the Community Hospital of San Bernardino.
They are in stable condition, said Jorge Valencia, director of business and marketing for the Colton hospital.
Loma Linda was caring for eight victims, five of which were sent directly to the hospital.
As of Monday afternoon, one adult male and one pediatric female were in critical condition; a male victim was in serious condition; and two adult females, a pediatric female, pediatric male and one adult male were listed in fair condition.
Flores said 36 passengers on the bus were residents of Tijuana.
Some of the passengers have contacted family members living in Southern California who are assisting them in returning to Tijuana.
"We are going to take them to Tijuana where they are coming from and some others, they are coming from Mexico City, so we're going to bring them to Mexico City and in regards to the people who died, we are going to pay (for their) funeral expenses, too," Flores said.