Huge bummer, nowhereman.
What caused the boiler to fail, interrupted fuel, failed pump, electrical fault? Even at -2 ( I assume F, or -19 C) to break the radiators that fast is crazy, even in an un-insulated farm house. Like you said, it must have been cooling when you checked it. How did you discover the five were broken, frozen up with no heat means no water running crossed the room to tip you off. Hopefully you can prevent more damage by containing the water as it thaws.