TMZ has obtained intense footage of the barn fire that killed "The Wire" actor Bobby J. Brown this week ... and it shows the large structure covered in thick smoke. Check out the clip ... firefighters are working hard to put out the blaze that erupted on the 50-by-100-foot barn in Chaptico, Maryland. You can still see flames ripping through the structure under the cloud of smoke ... and the roof is completely gone. A photo from the Office of the Maryland State Fire Marshal further highlights