混乱(hùn luàn) - chaotic, confused, chaos in Mandarin

混乱 (hùn luàn) covers disorder of any scale: a jumbled desk, a muddled train of thought, a city after an earthquake. It works as an adjective (很混乱) and as a noun (在混乱中), and Chinese moves between the two without changing the word.

Watch the company it keeps. 一片混乱 is the standard set phrase for a scene that has completely broken down, and 混乱起来 marks the moment order gives way. Neither needs 很 in front of it.

The English trap is severity. "Confusing" in English is often mild, as in a confusing timetable, but 混乱 is stronger and implies real breakdown. For a merely puzzling instruction use 不清楚 (bù qīng chu) or 让人搞不懂; save 混乱 for when things have genuinely come apart.