一發不可收拾

一发不可收拾
yīfābùkěshōushi
once it gets started there's no stopping it

CEDICT

to get out of hand

Wiktionary

一經發生，就很難制止或處理。

重編國語辭典

一旦發生，就難以制止或處理

維基詞典

Entry Composition

1 一發 yīfā
  1. along with all others; altogether
  2. even more
2 不可收拾 bùkěshōushi (idiom) irremediable; unmanageable; out of hand; hopeless