From far and wide, helpers pour into a fire-stricken San Diego

Rachel Hanley arrived in San Diego Wednesday after a 12-hour drive from her home in Colorado Springs, Colo. She parked her truck at the Del Mar Fairgrounds, home of the Del Mar Thoroughbred Club, and set to work caring for some of the more than 2,500 horses that have been given shelter there from the region's firestorm.

"There are a lot of displaced folks, but they seem to be taken care of," says Ms. Hanley. "But these animals are really scared, and not a lot of people can handle them. People are helping the fire victims of San Diego in all sorts of ways. Mine just happens to be with horses."

At least 1,000 volunteers have turned out in recent days, arriving at the fairgrounds and Qualcomm Stadium, evacuation central, to offer their services to the fire-besieged – everything from medical skills to yoga instruction.

Likewise, fire crews who've been battling the blazes since Saturday are seeing reinforce- ments arrive, as fires that had blackened nearly 500,000 acres by Thursday morning continue to burn throughout San Diego County. Eight deaths have been attributed to the southern California fires, and in a bit of bad news that represents the opposite spirit of the volunteer corps, authorities reported that arson is the suspected cause of two wildfires to the north – one in Orange County and one in Riverside County.

Among the firefighters who have worked to contain the San Diego fires are crews from Tijuana and Tecate in Mexico. "It is very important for Mexico to cooperate with the United States in situations like these because these fires affect the environment on both sides," said Capt. Marco Antonio Garambullo, Tecate's Fire Department director.

Mexico has also sent electricity to the area. A fire cut a main power link with Arizona, and a blaze near the Marine base at Camp Pendleton was, at press time, threatening the main north-south power corridor that connects San Diego with the rest of California.

The Mexican firefighters have since returned home to battle their own fires, but caravans of fire crews from northern California, Oregon, Idaho, and Washington continued to roll into San Diego on Wednesday. About 950 firefighters from the US Forest Service will arrive soon, the Federal Emergency Management Agency reported.

Away from the fire lines, average Americans with strong arms and big hearts threw their energies into helping all creatures, great and small, survive the fires as comfortably as possible.

Among those pitching in alongside Hanley to tend to displaced horses and other livestock were Future Farmers of America students from Eureka, Calif., who drove 700 miles nonstop to help.

At the stadium, where evacuees rested on cots and makeshift beds assembled on sidewalks, students from the University of Kentucky, Hawaii Pacific University, and Utah State University reported for duty. Church groups from Providence, R.I., and Yuma, Ariz., manned information booths and led prayer groups, and a motorcycle club from San Francisco roared into action, moving stacks of food and toiletries.

"I wanted to help because I couldn't do anything during the Katrina hurricane," says Dan Alves of Oakland, Calif., who adds that he had tried to volunteer in New Orleans but was turned away. "It wasn't as well organized. We went out there, but they said we couldn't help. This is a well-oiled machine."

San Diego Mayor Jerry Sanders, speaking Wednesday at Qualcomm Stadium, praised the volunteers and donors who have reached out to displaced residents. "This is the best of San Diego," he said. "This is where we take care of each other." Experienced medical personnel are still needed at all San Diego County shelters, Mayor Sanders added.

The American Red Cross is training 3,000 volunteers to lend a hand in coming weeks. So much food and water have been donated that officials at the fairgrounds and the stadium stopped accepting them Tuesday, asking for monetary donations instead. The two major evacuation centers are asking volunteers to help at smaller shelters.

Some of the 500,000 evacuees are being allowed to return to their neighborhoods, but others must remain in shelters or with friends until firefighters can contain – and then extinguish – the flames. That effort is unrelenting, and some firefighters at last were getting much-needed rest before returning to the fire lines.

"We sleep when we can, usually on the lawn," said engineer Randy Smith of Sacramento, encamped at Kit Carson Park in Escondido, command center for the Witch Creek fire. "Every time someone new arrives, it gets a little easier. But we all help each other and if this happens to us [in Sacramento] you'll see these same faces. It's what we do."

• Wire services were used in this report.