Some race tracks go for years without a driver fatality.
Irwindale Speedway has had two in its first six months.
Spectator fatalities were uncommon in recent years until three people were killed by a flying wheel and debris last year at Michigan Speedway.
Less than a year later, three people were killed at Charlotte Motor Speedway, again by a wheel that flew into the stands.
"Things happen, sometimes," said a prominent NASCAR official who asked for anonymity. "It sounds callous to say that, but sometimes there's nothing else that can be said."
Keith Cowherd, 49, a speed truck driver from Phoenix, died Saturday night of injuries suffered in a two-vehicle accident at Irwindale earlier that night. Shawn Davidson, the other driver involved, was hospitalized briefly, then released.
"It's devastating when something like this happens," Jim Williams, president of Irwindale Speedway, said Monday. "But racing is the business we have chosen to be in, and racing cars can be dangerous. We know that. It's unfortunate incidents like this happen. It's particularly devastating to those of us here at Irwindale, because we believe we have the safest and best-built short track in the country."
Casey Deimert, 23, was killed while practicing in a sprint car on opening night, March 27.
Saturday night's accident occurred on the seventh lap of the Speed Truck Challenge when '99 Chevy S-10s driven by Cowherd and Davidson tangled as they came off the fourth turn of the half-mile oval, traveling about 80 mph. Toward the end of the front straightaway there is an opening for the cars to exit the track.
At the break, the butt of the concrete retaining wall, four feet high and 12 inches thick, is protected by an energy absorber.
"It worked exactly the way it was designed to," said Ray Wilkings, who oversaw the building of the $6-million track. "Davidson's truck hit the wall flush on and the impact tore the body panels off the front half off his truck. It looked at the time like he was the one who would be hurt the worst."
Cowherd's truck, seemingly glued to Davidson's until impact, broke loose, spun around and slammed against the flat side of the wall.
Speed trucks are patterned after NASCAR super-late models, only with pickup truck bodies attached to stock car chassis. They weigh 2,600 pounds, including the driver, and put out 330 horsepower, about half that of NASCAR's Craftsman trucks, which weigh 800 pounds more and develop twice as much horsepower.
"The speed truck family can't believe what happened," said Mike Face, president and co-founder with Jay Rutherford, of the San Bernardino-based Speed Truck Challenge series. "In our inspection, we found that the integrity of the driver's compartment was intact on both trucks, and both had all four wheels still attached.
"The strange thing is that it appeared that Shawn hit much harder than Keith and he walked away from it. The loss really hit our guys. Keith was one of our most popular drivers, always striving to improve and to learn more about racing. He was a rookie in circle-track racing, but he had drag racing experience in the past."
This is the second year for speed trucks and Face said this was the first time a driver had been injured. Their schedule calls for 11 races at Irwindale, one the season finale Oct. 23, four at Orange Show Speedway in San Bernardino and one on the mile at Phoenix International Raceway.
After the accidents involving spectators, officials at both Michigan and Charlotte installed higher fences and stronger restraints, while the two sanctioning bodies, CART and IRL, made mandatory the use of tethers that keep wheels from flying off during an accident.
"I don't see where we can do anything to make our track safer," said Wilkings, who is leaving Irwindale on Friday to pursue business interests in Georgia. "When we were designing it, we talked to everyone in the industry, from drivers like George Snider and Parnelli Jones and Danny Sullivan to track operators like Roger Penske, Les Richter and safety experts like Bill Simpson. Everyone who has been here and seen what we have has marveled at the attention to detail, especially safety for both drivers and spectators.
"How do you account for a fatality at Laguna Seca, like the one they had [two weeks] ago, where it is considered the safest race track in America, or the [World of] Outlaws driver who was killed last Friday night. In . . . racing, you realize it may happen. It's never easy, but sometimes it is inevitable."
Rookie driver Gonzalo Rodriguez of Uruguay was killed in a single-car accident during practice for a CART race at Laguna Seca. Kevin Gobrecht, one of sprint car racing's most promising drivers, was killed while racing in a World of Outlaws event at Greenwood, Neb.
Speedway officials plan a tribute to Cowherd during Saturday night's U.S. Auto Club program.