Reporting an Aviation Accident

The Canadian and US regulations state reporting procedures and the
conditions under which a accident plane can be moved. But what is the
procedure for this scenario:

Two planes are involved in a midair enroute from Canada to the US. The
midair happens in Canadian Airspace but the planes land in the US. Both
planes are seriously damaged. Is it an offence to land anywhere but the
nearest suitable airport? Which authority must be notified? Once the
planes have landed, can they be moved from the place they stopped without
permission from the investigating authority? (i.e. Moved from the ramp to a
hangar.)

Le Moo