Widespread tsunami waves are possible after a magnitude 8 earthquake struck off the southern coast of Mexico.
People in the capital, Mexico City, ran out into the street in their pyjamas after the tremor shook buildings.
Lights have been extinguished in part of the city.
It struck at a depth of 21 miles (33 km), 76 miles (123 km) southwest of the town of Pijijiapan.
The Pacific Tsunami Warning Centre said there was a danger of hazardous tsunami waves.
“I had never been anywhere where the earth moved so much,” said 31-year-old architect Luis Carlos Briceno who is visiting Mexico City.
“At first I laughed, but when the lights went out I didn’t know what to do. I nearly fell over.”
It is the strongest earthquake to hit Mexico since a devastating tremor in 1985 that toppled buildings and killed thousands, the country’s civil protection agency said.