October 9, 1963, 10:39 PM. A blinding flash, a terrifying roar. Mount Toc collapses into the lake, raising a terrifying wave of water. It rises hundreds of meters above the dam, overflows, and crashes down on the town of Longarone and its hamlets, wiping them from the face of the earth. Upstream from the dam, another wave surges violently from one side of the valley to the other, sucking the villages of San Martino and Spesse into the lake and damaging the towns of Erto and Casso. The story of the "great Vajont," which had lasted twenty years, ends in three minutes of apocalypse, with the holocaust of two thousand victims.

To this day, the Vajont disaster remains one of the "natural" man-made disasters in Italy. The dam remained intact after the tragedy and was left as a reminder of human arrogance, which sacrificed thousands of innocent lives for vile profit. Of the nearly 2,000 victims, at least 300 were children.

More info here: https://en.wikipedia.org/wiki/Vajont_Dam