LONDON (AP) — People across Britain fell silent to mark 50 years since a mountain of coal sludge collapsed onto a Welsh village, killing more than 140 people in one of the country's worst mining disasters.

On Oct. 21, 1966, a mine dump above Aberfan collapsed, sending 2 million tons of waste cascading downhill, demolishing 18 homes and Pantglas Junior School. The wave of rubble killed 116 children and 28 adults.

Welsh First Minister Carwyn Jones said it was "a truly heart-breaking moment in our history, and no one who learns about the disaster can fail to be profoundly moved by it."

A minute's silence was held Friday at 9:15 a.m., the exact moment disaster struck.

Later, Prince Charles is due to meet survivors and unveil a plaque in memory of the victims.