at that very moment; just when
Fixed phrase emphasizing a timely or coincidental moment. Often used with と or に to set the scene for something happening.
折も折、彼から電話がかかってきた。
At that very moment, he called me.
Just at that moment, it started raining.
Reduplication of 折 (おり, 'time, occasion') with the particle も, literally 'time also time', emphasizing the exact moment.