Here’s the dispatch audio from the fatal barn fire that killed “The Wire” actor Bobby J. Brown … and you hear dispatchers saying he’s trapped in the building after trying to start an old Cadillac.

TMZ obtained the dispatch audio, which also reveals Bobby’s wife called for help. It sounds like a huge inferno, the barn is 50-feet-by-100 and — by the end of the call — it’s all up in flames.

We broke the story … Bobby died Tuesday from smoke inhalation. The deadly fire started after Bobby entered the barn to jump-start a car. His wife suffered severe burns trying to save him.