SAN DIEGO -- A 21-member contingent of state firefighters based in San Diego County departed Tuesday to help fight stubborn wildland conflagrations in Northern California.

The men and women, who left Cal Fire's San Diego-area headquarters near El Cajon aboard a chartered bus in the late morning, will relieve colleagues who have been battling fires nonstop for 35 days, said Nick Schuler, a captain with the agency.

Among the blazes the personnel have worked are the Basin Complex Fires, which began spreading through Los Padres National Forest and Big Sur in Monterey County on June 21.

The fires have blackened about 120,400 acres, destroyed 27 homes and injured nine people. They were 61 percent contained as of Tuesday morning, and officials project full containment by July 30.

The replacement San Diego-area crew could be on the special assignment for as long as 42 days, if necessary, the captain said.

The rotation will give the preceding group a much-needed break, according to Schuler.

"(Commanders) want to ensure that safety is the number one priority, and they want to ensure that (personnel) get some rest," he said.

Schuler stressed that Cal Fire officials have made sure to keep a sufficient staffing level in the San Diego area.