Here are some images depicting air drops from the fixed-wing air tankers. One is a Lockheed P-3 Orion which is capable of  dropping 3,000 gallons of fire retardant, and the other is a McDonnell Douglas DC-10 which can carry 12,000 gallons of water or retardant.

Some data on the DC-10 from CALFIRE:

• Originally delivered as a civil passenger plane to National Airlines in 1975, it subsequently flew for Pan Am, American Airlines, Hawaiian Airlines and Omni International.

• The DC-10 is the only wide-body jet air tanker currently in the fire service. The aircraft, operated by 10 Tanker Air Carrier, is used for fighting wildfires, typically in rural settings. The turbofan-powered craft carries up to 12,000 gallons of fire retardant in an exterior belly-mounted tank, which can be released in eight seconds. This aircraft will not be used on all fires, and will not be used on initial attack. It is utilized in extended attack fires as it is limited in time effectiveness for reloading fire retardant as well as its need to reload and refuel at an equipped aerial firefighting base (currently Victorville and McClellan are the only bases in California serviceable for this large an aircraft). One drop for the DC-10 is equivalent to 12 drops of an S2-T or a line of retardant that is 300 feet wide by one mile in length.

Fire is burning in the hills near Diamond Bar, CA in 2008 as part of the Freeway Complex Fire. Larry Shapiro photo

An example of the homes in the evacuated neighborhood in Diamond Bar. Larry Shapiro photo

P3 Orion air tanker working at the Freeway fire in 2008. Larry Shapiro photo

DC-10 outfitted for firefighting operations flies low over the neighborhood as it lines up for a drop. Larry Shapiro photo

Following it’s lead plane, the DC-10, begins it’s drop. Larry Shapiro photo

Capable of dropping retardant over an area a mile long, the DC-10 continues to spread retardant. Larry Shapiro