At least five people died in a historically massive earthquake that struck the southern coast of Mexico early Friday, toppling hotels and houses and prompting tsunami waves and power outages. The United States Geological Survey said that a magnitude 8.1 quake hit about 73 miles off Tres Picos, Mexico, along Mexico's southern coast. Its epicenter was 102 miles west of Tapachula in southern Chiapas state and had a depth of about 21 miles. The quake was so powerful, it sent people fleeing from buildings 650 miles away in Mexico City.