Newbie: alter system kill session and save their SQL:s?

Hi,

I have manage to check the database after a specific wait, if the wait exists, check if the session with the waits is blocking other sessions, if it does, I kill the session.

This is the part where I kill the blocking sessions:

loop

   if (blockingsessions.s1 > sessionvalue) then

   for rec3 in (SELECT 'alter system kill session '''|| sid || ',' || serial# || '''' stmt FROM v$session where sid=blockingsessions.s1)

   loop

   execute immediate rec3.stmt;

   end loop;

  var_event:='Killed sessions!';

   insert into maintenance.logtable values (SYSDATE,var_event);

   commit;

   end if;

What I would like is help on how to capture the SQL that was causing the block.