MEXICO CITY — One of the most powerful earthquakes ever recorded in Mexico struck off the country’s southern coast, toppling hundreds of buildings and sending panicked people fleeing into the streets in the middle of the night. At least 61 people were reported dead.

The quake that hit minutes before midnight Thursday was strong enough to cause buildings to sway violently in the capital city more than 650 miles away. As beds banged against walls, people in pajamas ran out of their homes.

The furious shaking created a second national emergency for agencies already bracing for Hurricane Katia on the other side of Mexico, expected to strike the Gulf coast late Friday or early Saturday as a Category 2 storm that could bring life-threatening floods.

President Enrique Pena Nieto said Friday evening in a televised address that 61 people were killed — 45 in Oaxaca state, 12 in Chiapas and four in Tabasco — and he declared three days of national mourning.

The worst-hit city was Juchitan, on the narrow waist of Oaxaca known as the Isthmus, where 36 quake victims died.