Five separate fires started shortly after 1:30 p.m. along the railroad tracks near Knightsen Avenue and Eden Plains Road, fire officials said.
Henderson said fire investigators were working with the railroad operator to see if a train could have sparked the fires, but had yet to come to any conclusions.
Between 75 and 80 fire personnel responded to the four-alarm incident and were able to protect about a dozen homes that were threatened by the flames, Henderson said.
Firefighters had the blaze under control shortly after 3 p.m.
Henderson said the area that burned was mostly grass with some eucalyptus trees and brush.
Luckily for firefighters, temperatures were only in the 80s with a light wind. Flat terrain and some humidity also helped firefighters get the upper hand on the fires.
Henderson said it would most likely be several days before investigators determined a cause of the fires and worked out a damage estimate.