行き成り

いきなり

abruptly, suddenly, all of a sudden, without warning

JLPT N2

Details

Part of Speech:: Adverb , Noun which may take the genitive case particle 'no'
Romaji:: ikinari

急に雨が降り出して行き成り雷も鳴り始めた

It started raining and suddenly a loud thunderclap began

行き成り大声で叫んだら、周りがびっくりした

I suddenly shouted loudly, and those around were surprised