There is meant to be a rough count of 10,000 Jedi in the Star Wars Galaxy (which sounds a lot,but it pitifuly few compared to the uncountable total population). It's going to be a right pain to even come up with a vague way of killing all of them inside the films.
Published Star Wars timelines maek out that Vader hunts down and destroys the Jedi between episodes III and IV. of course, these timelines are liable to be wrong, and even in 20 years it doesn't seem practical for one man to do the work.
Though if a load of them go out to a big bomb or orbital attack or something, there must have been a major failing of the fabled Jedi danger sense...
Oh I don't know if there's a major flaw with the Jedi danger sense..sometimes things happen and you can't really stop them..even when you know about them.
As for Vader wiping out all the Jedi. It would seem most likely that Vader's subordinates did alot of the killing, though I'm sure Vader himself would be directly responsible for more than a few of the deaths himself.
Welcome to the forum Ushgarak (in case I didn't say that before) 🙂