Los Angeles is a sprawling and complicated place. The city measures more than 450 square miles, and the county is even larger. The two are woven together geographically, and fires, of course, do not respect boundaries on a map.

As such, the effort to fight the multiple fires raging across the Southland has required coordination between many agencies. At a joint news conference organized by county officials on Wednesday morning, some 10 agency department heads were allotted time to speak.

But two leaders who have emerged as among the most critical to the firefighting effort are a pair of fire chiefs: Anthony C. Marrone, the fire chief for Los Angeles County, and Kristin M. Crowley, the chief of the city’s fire department. The two top fire officials are working in what is known as “unified command” with a third key group, California Department of Forestry and Fire Protection, the state fire agency known as Cal Fire.

A spokeswoman for the Los Angeles Fire Department said on Wednesday that the department was responsible for the Palisades fire, which was burning in the neighborhood of Pacific Palisades, and the Hurst fire, which was cutting through the San Fernando Valley and concentrated in the Sylmar neighborhood, also within city limits.

“We are absolutely not out of danger yet,” Chief Crowley said at the news conference.

Cal Fire has assigned what is known as an incident commander to each fire, though a spokesman at a command post in Malibu said on Wednesday afternoon that it was not yet clear who those commanders were.

A third fire, the Eaton fire, is ripping through the Angeles National Forest, the Altadena area of Los Angeles County and part of the city of Pasadena. That blaze falls under the jurisdiction of Chief Marrone and the Los Angeles County Fire Department. Chief Marrone is also a regional fire coordinator who said he had asked for help from nearby counties and the state office of emergency services.

“Please prioritize your safety,” Chief Marrone said at the news conference.

Chief Crowley, a 22-year veteran of the department, became the first female and L.G.B.T.Q. chief of the city’s fire department when she took the oath of office in March 2022.

Chief Marrone has worked with the county fire department for almost 40 years and has worked as a chief officer there for more than two decades.