At 9.08 on the night of 13 November, 20 million cubic metres of lava exploded from Nevado del Ruiz. Snow and ice on the summit of the volcano quickly melted, and mud, water, ice and lava poured into the rivers that surround the volcano. The rivers became walls of mud up to 30 metres high and travelling at 50 kilometres an hour. The people of Armero had no chance to leave the town and climb to safety in the nearby hills. Two and a half hours after Nevado del Ruiz erupted, the town of Armero was buried in mud and more than 23000 people were dead. If the scientists' warnings hadn't been ignored many lives could have been saved.