Rappers Juicy J and Project Pat -- Music Video Derailed After Skylight Accident

Project Pat and Juicy J's video shoot came to a crashing halt ... after a crew member fell through a skylight, crashing to the ground around 20 feet below.

The former Three 6 Mafia member and his brother were filming on the roof of a very old art deco building in Vernon, CA when the accident occurred.

Apparently the crew member wasn't looking as he hit the skylight ... shattering it.

Paramedics were called and the crew member was rushed to the hospital, where he was treated for rib and chest injuries.

It could have been a lot worse. He barely missed 2 porcelain sinks.