This already likely was a coup. They knew exactly where Maduro was and were able to get in and out, with no air defense issues, no alarm issues, and all presumably with just a small commando group. This isn't like grabbing Osama who was relatively alone on a compound - this is the current President of a country, who was already probably quite paranoid, and who now was under active threat and certainly behaving accordingly. Doing all that as an outsider is basically impossible, so they must have had substantial amounts of insider help, which is essentially the definition of a coup.

And the media is already reporting that 'somehow' all of his inner circle seem to have survived.