is there a way to break a trigger chain?

on a table, i've got 3 triggers after update. First is not revelant

second does:
if (new.qty = 0) then
delete from mytable where id = new.id

third does:
if (new.field = 'T') then
execute procedure update_mytable;
else
execute procedure update_othertable;

the problem is that, sometimes, update_mytable assign 0 to the field qty.

so i've got an error saying "too many execution of the same query" (not
sure about the message but sense is there)

the solution i used to solve my problem was to change the third trigger to

if ((new.field = 'T') and (new.qty > 0)) then
etc

except using an exception, is there a way i could use to break the
trigger chain ?

Thierry