I think that would depend on the individual fire department.
Don't be confused here. This was not ARFF responding. Sounds like the airport does not have ARFF capability. This is just the local fire department responding to a call.
As for the time frame, that depends on the fire department, time of day, who was at the station, etc. My township is technically volunteer firemen with staff EMTs/Paramedics, but there is always someone at each of the stations at all times.