(CNN) -- An off-road race in southern California's Mojave Desert became a scene of horror over the weekend when a truck crashed into a crowd of spectators along the roadside, killing eight people, authorities said Sunday.
The crash at the Saturday-night race left six people dead at the scene, said Tim Franke of the San Bernardino County Fire Department. The California Highway Patrol said Sunday the final death toll was eight.
Four more were taken to hospitals by air in serious condition, while five others suffered minor to moderate injuries.
The 200-mile race was part of an amateur series on a course in the Lucerne Valley area of San Bernardino County, east of Los Angeles, Franke said.
Vince Dimiao, a driver who was running just ahead of the truck that crashed, said the races are often run at night due to the extreme heat. He said officials initially halted the race for an hour due to the crash, then canceled it completely when the scope of the "carnage" became known.
The race's sanctioning body, Mojave Desert Racing, urges spectators to stay back 100 feet from the 50-mile course -- "But as you can tell, there are no delineations to where the track begins and where the track ends at this point," said Joaquin Zubieta, a California Highway Patrol spokesman.
Dimiao said there are few restrictions on spectators, and Larry Webster, automotive editor for Popular Mechanics magazine, said few such races remain "precisely for this problem."
"It's just very difficult to control the spectators," Webster told CNN. "You can give all the warnings you want, but at the end of the day, they're out there, they're on their own and they do what they want."
But Rich Minga, a former off-road racing champ, defended the sport on Sunday.
"This sport's been safe throughout the years," he told CNN. "We have a wonderful track record -- it's been a great, great form of family entertainment."
Minga said it was "quite shocking" how close the spectators at Saturday's Lucerne Valley race were to the course, but acknowledged that fans frequently gather at points "where the cars might be apt to do something more exciting."
Minga said he supported an investigation of the incident "so we could put more safety measures and keep it a little bit safer."
Jonathan Davy, who attended Saturday's deadly race and captured the accident on video, said he sensed the danger even before the crash.
"They have barricades up... to hold the fans back and the spectators and it still doesn't control the situation with the fans because they want to get as close as possible to what's going on," Davy told CNN. "It's really intense -- everybody's going 'Go faster, go faster, go faster!' and a lot of people hit these jumps and get air and everyone cheers and it's just crazy."
"Even for me to be right there filming was very dumb," he said. "(I) was just in the moment."
Davy said it was his first off-road race.
"What seemed to be like a great day... something I had never been to before, just turned tragic," he said. "It 's forever going to be in my head. I couldn't sleep last night. I got chills right now just thinking about it."
CNN's Nick Valencia and Chuck Johnston contributed to this report.