あれよあれよという間に
Meanings
1
before one knew it; in the blink of an eye; while looking on in amazement
Describes a situation that unfolds surprisingly quickly, often leaving the speaker or observer stunned or unable to react. The phrase carries a nuance of bewildered amazement at how fast events progressed.
See also: あれよあれよ
Before anyone knew it, he had risen all the way to company president.
In the blink of an eye, the fire spread throughout the entire house.