Nine-Tailed Demon Fox's Attack

Twelve years before the start of the series, after the end of the Third Great Shinobi World War, the Nine-Tailed Demon Fox attacked Konohagakure.

Attack
The attack of the Nine-Tails coincided with Kushina Uzumaki, the second jinchūriki of the Nine-Tails, giving birth to Naruto on the night of October 10th. With the previous jinchūriki's seal almost breaking during childbirth, the village took multiple precautions; it was carried out in secret, with Biwako Sarutobi, the Third Hokage's wife, as her midwife, a few ANBU as security, and with Minato keeping the Four Symbols Seal holding the Nine-Tails secure, along with one of the most powerful and secret barriers that the village had to protect them.

The location was eventually discovered by Madara Uchiha, who then killed the ANBU and Biwako, and held the newborn Naruto hostage. While holding Naruto at knife point, Madara ordered Minato to walk away from Kushina. Minato tried to negotiate with Madara, as the seal began to weaken. Kushina pleaded with Minato to protect Naruto. It was at this moment that Madara attempted to stab Naruto. Before the knife could hit Naruto, Minato was able to snatch Naruto away from Madara. But to his surprise Naruto's baby clothes were filled with exploding tags, forcing him to use the Flying Thunder God Technique and transport himself and Naruto away from the explosion but also away from Kushina.

With Minato away from Kushina, Madara used a technique to extract the Nine-Tails from Kushina. He hurried the extraction as he noted that the seal holding the Nine-Tails also had carried the Flying Thunder God technique seal, so Minato would not be far behind him in trying to rescue Kushina. As the Nine-Tails emerged from the seal, Madara used his Sharingan to gain control of the Nine-Tails. Before he could set off to destroy Konoha, Kushina, barely alive from having a tailed beast extracted from her body, struggled to speak and begged Madara to stop. Madara directed the Nine-Tails to crush her but was rescued from being crushed by the large paws of the Nine-Tails by the arriving Minato. They soon escaped back to Naruto's secret location where he set Kushina beside Naruto before heading off to protect the village of Konoha.

The Nine-Tails' strength at this point was so great, that even far away from the village, a young Itachi Uchiha, along with several other shinobi, were able to sense its presence. Madara, under the cover of night, sneaked into the village, and with the use of the Summoning Technique, summoned the Nine-Tails into the village without warning. Shinobi and villagers inside of Konoha were frightened as they recognized the Nine-Tails as it caused destruction and casualties instantly. When the Third Hokage felt the familiar power and malevolence of the Nine Tails, he immediately prepared for battle, even as the ANBU arrived to inform him of the Nine-Tails attack. He orders shinobi nearby to prepare to defend the village.

Counter-Attack
Minato arrived on top of the Hokage Monument, and the Nine-Tails quickly noticed him, and attempted to kill him using a large blast of chakra. Minato, using a Space-Time jutsu, teleported the blast away from the village, causing other shinobi to be aware of his presence. Before Minato could tell the Third of what had happened to Kushina, Madara teleported to his location and attempted to use his own jutsu on Minato, with Minato barely escaping by using the Flying Thunder God Technique to teleport away from the village. Madara followed him, and after analyzing his abilities, Minato asked if he was Madara Uchiha. Giving no definite answer, Madara attacked Minato, both of them using their own Space-Time jutsu to avoid capture. Eventually, using a kunai that he barely threw behind Madara, Minato teleported behind Madara and got a hit using the Rasengan.

Nobody was able to stop the Nine-Tails, only stall it, until Minato arrived to apply the seal on the Nine-Tails; sealing the Yang portion of the Nine-Tails' chakra into Naruto while keeping the Yin portion within the Death God. Kushina's involvement in the sealing process is yet to be seen, as she seemingly had contributed her chakra and soul into the sealing of the Nine-Tails into Naruto.

Aftermath
The village suffered heavy casualties during the attack, such that few of the villagers would forgive Naruto (who they viewed as the fox) for its actions despite the fact that he was the one who contained the beast. Because the Fourth Hokage died during the attack, and having no suitable candidates at hand, the Third Hokage was forced to retake his position, despite his age.

As the Uchiha clan's Sharingan is able control the Nine-Tails, the elders of the village suspected them of being responsible of unleashing the attack. It was this spite that led them to attempt a rebellion, which ended with their mass assassination before it could happen. During the attack, Itachi noted that his parents were noticeably absent before the beast struck. What they were doing is currently unknown.

In the anime, the Nine-Tails is revealed to have left behind large amounts of its chakra during the attack that, when gathered by Kazuma, allowing him to turn Sora into a pseudo-jinchūriki.

Claims
Though the Nine-Tails had attacked many settlements regularly throughout history for no apparent reason, Jiraiya, and Itachi Uchiha speculate that Madara Uchiha was behind the attack on Konoha, while Minato and Kushina were personal witnesses to his involvement. Madara denies this to Sasuke Uchiha and attributes its rampage as a natural occurrence. However, Minato claims to have fought him on the night of the attack, and Kushina tells Naruto that a "masked man" took control of the Nine-Tails.