SAN DIEGO, Oct. 23 (UPI) -- U.S. Homeland Security Secretary Michael Chertoff said border security had not been degraded by a major wildfire raging in Southern California.

Chertoff told reporters in San Diego Tuesday that Border Patrol agents were filling the gap left when about 200 California National Guard troops assigned to the border were pulled out in order to help with the firefighting efforts.

The secretary, who was in San Diego as part of the federal response to the fires, called on the Mexican government to urge anyone thinking of slipping into the United States amid the confusion to think again.

“They would be taking an incredibly foolish risk,” Chertoff said. “They need to make it clear to everyone that being in the area of the border with an unpredictable fire going on is incredibly dangerous.”

The Harris (NYSE:HRS) fire, the southern-most blaze in the ongoing series of Southern California wildfires, was not threatening Mexico. San Diego County Supervisor Ron Roberts said earlier Tuesday that he had spoken to the mayor of Tijuana, Mexico who offered to send whatever assistance the Americans might need.