Before Oakland Tragedy Ex Worker Warned Art Collective Was Primed for Disaster

The Oakland fire was 100% avoidable in the eyes of a woman who worked in the building ... and claims she warned the boss about safety dangers for years.

Danielle Bourdeaux volunteered at the so-called Oakland Ghost Ship art collective until 2015, and says she was friends with its director, Derick Ion, and his family. However, she paints a very vivid picture of "dangerous, disheveled" -- conditions she says she warned Ion about multiple times.

She believes Ion is a "hoarder" who blew off her concerns, and added ... that infamous cargo pallet stairway in the building was more like a "treehouse staircase." She revealed there was a more legit one, but explained why it wouldn't have helped first time visitors.

Bourdeaux says she left the collective after a falling out with Ion over his kids. Basically, she felt it was unsafe for them to live in the building, and she claims he disagreed.

We've reached out to Ion, but haven't heard back. Cops have not named any suspects, but say criminal charges are a possibility. They continue searching, and the death toll is now at least 33.