Insert into select into multiple related tables using INSERT_IDENTITY
A solution that might work for you is using the OUTPUT clause, which spits out all the inserted rows, so you can re-insert them into a different table. However, this puts limitations on foreign key constraints on Table2, if memory serves.

Anyway, the solution would look something like this:

MERGE INTO Table1 AS t1
USING MyTable ON 1=0 -- always generates "not matched by target"

WHEN NOT MATCHED BY TARGET THEN
    -- INSERT into Table1:
    INSERT (A, B, C) VALUES (t1.A, t1.B, t1.C)

--- .. and INSERT into Table2:
OUTPUT inserted.ID, MyTable.D, MyTable.E, MyTable.F
INTO Table2 (ID, D, E, F);


MERGE, as opposed to the other DML statements, can reference other tables than just inserted and deleted, which is useful for you here.

More: http://sqlsunday.com/2013/08/04/cool-merge-features/