In that case you might be able to attack the fire with two people and two exinguishers at the same time.
If the fire is two big for that, there are severe risks due to rapid spreading of the fire, toxic fumes and smoke. There is a reason why professionals have a mask and air tanks. By the time you haul the second pair of extinguishers the fire may already be beyond what you can control.
Trying to put it out anyway would nicely fit in the topic "What not to do in a disaster".
I second choasmagnets advice.