They were lucky that it was that time of day and they got such large turn out, if it have been during the day, when people were working it could been alot less!
And that would be why they needed 3 departments. We have had mutual aid calls where the aiding department had more people show up than the department that asked for help; which is the reason they had to ask in the first place. There are 2 areas in our county where we know if it's during the day, where 1 department goes, the one "next door" will end up going with them.