Jockey dies after fall at California track A jockey fell when a horse clipped another horse and stumbled Jorge Herrera died from a head injury Jockeying is the most dangerous sport, an official says; accidents kill about two jockeys a year (CNN) -- A jockey who had raced more than 1,000 times died Thursday night after falling from his horse during an event in Pleasanton, California. Jorge Herrera, 33, died at Eden Trauma Center in Castro Valley from a head injury. He was racing in his second event of the day when he was thrown from his horse, Morito, which appeared to clip the heels of another horse and stumble. Herrera lurched forward and went over Morito's head as the horse righted itself and continued. "He was stepped on by either his horse or another horse and suffered severe head trauma," April Mitchell, a spokeswoman for the Alameda County Fair Association, told CNN affiliate KPIX. We deeply mourn this loss today. An ambulance was following the horses and medical personnel responded immediately, a statement from the association said. Herrera was a quiet, polite man who generally kept to himself, said Darrell Haire, regional manager for the Jockeys' Guild. "He was a nice kid; everybody liked him," he said. Like a lot of riders he was trying to get started and get lucky. He didn't get the opportunities that a lot of guys get. Haire said he thought Herrera, originally from Mexico, lived with an uncle. It isn't uncommon for horses to clip heels during a race, Haire said. "A lot of times when they clip heels they'll stumble, but when they clip just right they'll do a nose dive," he said. It's like a crash. They just go down. It also isn't uncommon for jockeys to fall, though usually they'll break collarbones and shoulders, or injure their backs, he said. And sometimes they die. A lot of people don't realize that," he said. It's part of the game, part of the occupation. Jockeying is the most dangerous job in sports based on the number of deaths and injuries, said Terry Meyocks, national manager for the Jockeys' Guild, based in Nicholasville, Kentucky. Since 2007 there have been five deaths -- including Herrera -- and last year 19 percent of the active riding members of the guild were out on temporary disability. There are roughly 650 active riders in the guild. Within the past month the guild has begun work on a jockey injury database, which looks not only at the number of injuries, but at the racing conditions and what gear the rider was wearing, Meyocks said. The goal is to find patterns that might help prevent injuries in the future. Meyocks said there have been about two jockey deaths per year in the United States -- 152 total -- since the guild started compiling a fatalities database in 1940. Herrera had 1,010 thoroughbred mounts and 55 victories in his career, according to equibase.com. He had been injured three times, Meyocks said. The guild is looking into what those injuries were. Herrera's death came 37 years to the day after the last previous death of a jockey -- Juan Gonzalez -- in an accident at the track. Mitchell said racing would begin at its usual time on Friday and "planning for a tribute is still under way."