A 12-year-old boy died Monday from head injuries suffered while skateboarding in the Ashland neighborhood of unincorporated San Leandro, authorities reported Tuesday.

The boy, Jose Heriberto Trujillo of San Leandro, and a friend were racing on their skateboards down a steep incline on 165th Avenue at about 2:30 p.m., Alameda County Sheriff's Lt. Kelly Miles said. They reached speeds of around 20 mph when both boys lost control and fell onto the pavement, Miles said.

Neither was wearing a helmet, he added.

"It's tragic," Miles said. "Unfortunately, accidents like this happen. I think it is agreed that he would have had a lot better chance if he were wearing a helmet."

Miles said Jose was taken to Children's Hospital in Oakland, where he was pronounced dead at 3:30 p.m.

The second boy, whose identity was being withheld, suffered minor scrapes in the fall, Miles said.

The steep incline on 165th Avenue stretches from Liberty Street to about 150 yards down the hill. The boys fell about halfway down the incline. A speed hump is located on the street at the bottom of the incline, where the street flattens.

Alfredo Mata, who lives near the bottom of the incline, said he sees children speeding down the hill on bicycles and skateboards nearly every day, and that he has never seen any of them wearing helmets. "Sometimes there are a lot of kids on the hill close to the cars," Mata said. "They have fun like that."

He noted that he had seen the two boys riding their skateboards down the hill before, and that he had heard of other children falling on the hill, but none of them had ever died as a result.

Kevin Wooden, who lives on 165th Avenue, said he witnessed the fall.

"Kids always ride skateboards down the hill," he said. "Usually, they sit on their skateboards, but this time he stood up."

There is a helmet law in California for skateboarders under age 18. Section 21212 (a) of the California Vehicle Code stipulates that minors must wear a helmet while riding bicycles, skateboards and scooters. Violations are punishable by a fine of no more than $25. Parents or legal guardians are jointly liable for the amount.

"Usually, if they allege in court that it's their first violation, they are basically let go with a warning," Miles said. "After that, it's a $25 fine."