SAN DIEGO, Oct. 26 — Out of the burning brush, from behind canyon rocks, several immigrants bolted toward a group of firefighters, chased not by the border police but by the onrush of flames from one of the biggest wildfires this week.
Their appearance startled the firefighters, who let them into their vehicles. But with the discovery of four charred bodies in an area of heavy illegal immigration, concern is growing that others may not have survived.
“Their hands were burned, and they were clearly tired and grateful,” Capt. Mike Parkes of the State Department of Forestry and Fire Protection reported on what his firefighting team saw.
Immigrants from south of the border, many illegal, provide the backbone of menial labor in San Diego, picking fruit, cleaning hotel rooms, sweeping walks and mowing lawns.
The wildfires, one of the biggest disasters to strike the county, exposed their often-invisible existence in ways that were sometimes deadly.
The four bodies were found in a burned area in southeastern San Diego County, a region known for intense illegal immigration. It is near Tecate, where a chain securing an evacuated border crossing was cut and people were seen flowing into the United States until the Border Patrol arrived, said Michael J. Fisher, the chief patrol agent in San Diego.
As firefighting continued on Friday, makeshift camps for immigrants in the northern part of the county stood largely abandoned. Some immigrants were said to be hiding in even more remote terrain. Others sought help from churches.
“I was pretty scared. We had to leave in the middle of the night, and we went to the church,” said Juan Santiago, a immigrant worker in the Rancho Peñasquitos neighborhood, just south of the hard-hit Rancho Bernardo area.
Terri Trujillo, who helps the immigrants, checked on those in the canyons, urging them to leave, too, when she left her house in Rancho Peñasquitos ahead of the fires.
Ms. Trujillo and others who help the immigrants said they saw several out in the fields as the fires approached and ash fell on them. She said many were afraid to lose their jobs.
“There were Mercedeses and Jaguars pulling out, people evacuating, and the migrants were still working,” said Enrique Morones, who takes food and blankets to the immigrants’ camps. “It’s outrageous.”
Some of the illegal workers who sought help from the authorities were arrested and deported. Opponents of illegal immigration, including civilian border watch groups, seized on news that immigrants had been detained at the Qualcomm Stadium evacuation center as evidence of trouble that illegal immigrants cause.
The Border Patrol also arrested scores of illegal immigrants made visible by the fires. Agent Fisher of the Border Patrol said 100 had been arrested since the fires started Sunday.
He said that the agency never abandoned enforcing the border and that agents helped with removals and rescues. Fire blocked some access points to border areas, but Agent Fisher said, “We were very conscious in making sure our border security mission was met.”
Some people have speculated, including on the Web, that immigrants might have set some of the fires, as has occurred with campfires lighted in fields.
The authorities have not given any causes linked to immigration.
Two men, one in San Diego County and the other in Los Angeles, who were arrested on arson charges, accused of setting small fires this week, are believed to be deportable, a federal immigration official said.
The San Diego police detained people suspected of stealing at Qualcomm Stadium. Six were handed over to the immigration authorities when it became apparent that they might be in the United States illegally.
The Border Patrol said the six, and at the group’s request, an American juvenile with them, were returned to Mexico.
The American Civil Liberties Union said it had received reports that people had been denied help at shelters because they lacked proper identification. Officials have been checking identification to prevent people not affected by the fires from taking advantage of the free food, clothes and other services.
The concerns of the rights group drew a rebuke from Representative Brian P. Bilbray, a Republican who represents areas along the border.
“People are dying because we can’t control our border,” Mr. Bilbray said. “That’s what they should be screaming about. Anyone who knows the land and the illegal activity in that rugged terrain knows there was no way we would avoid deaths in this.”
Wayne A. Cornelius, a political scientist at the University of California, San Diego, who studies border questions, said that if the past was a guide there would be more friction over the fires and their effects on illegal immigrants.
“San Diego likes its illegal migrants as invisible as possible,” Mr. Cornelius said. “So whenever something happens that calls attention to their presence, it is fodder for the local anti-immigration forces.”
In one sign of cooperation, a Mexican firefighting team from Baja California helped American firefighters with a major blaze along the border early in the week.
For the immigrants, the fires may have dried up some work. But some speculate on strong work prospects like cleanups. By early afternoon near a heavily damaged neighborhood in the Rancho Bernardo area, four men stood on a corner, waiting for work offers.
“It is a shame what happened,” said a man who gave just his first name, Miguelito. “But we think there will be jobs to clean or build.”
