"Naruto's Birth" (ナルトの出生, Naruto no shusshō) is chapter 500 of the original Naruto manga.
Summary
Kushina's tells Naruto the history of her clan, and how she became the second Nine-tails jinchūriki. After that she begins to explain the events that happened on the day of his birth sixteen years ago.
Soon after Naruto's birth, a masked man killed all the ANBU guarding the cave where he was born. He took Naruto hostage, and told the Fourth Hokage to step away from the jinchūriki, or he would kill the new born.