Widespread "hazardous" tsunami waves were possible after a huge, magnitude eight earthquake struck southern Mexico, the Pacific Tsunami Centre has warned.
People in Mexico City fled buildings as tremors rattled the country's capital. As buildings swayed, lights were knocked out in parts of the city.
"I had never been anywhere where the earth moved so much. At first I laughed, but when the lights went out I didn't know what to do. I nearly fell over," said Luis Carlos Briceno, a 31-year-old architect.
Mexico's civil protection agency said it was the strongest earthquake to hit the country since a devastating 1985 tremor that toppled buildings and killed thousands.
The US Tsunami Warning System said waves "reaching more than three meters" were possible along some of Mexico's coast.
The earthquake was a potential tsunami threat to several Central American countries, including the Pacific coastlines of Guatemala, Honduras, Mexico, El Salvador and Costa Rica, it said.
It added that the threat was still being evaluated for Hawaii, Guam and other Pacific islands.
The United States Geological Survey (USGS) said the earthquake's epicentre was over 600 miles away near the small town of Pijijiapan in southern Chiapas state. It was at a depth of around 20 miles, it added.
The stretch of the Mexican coast that felt the impact most strongly is thinly populated, but to the west the popular resorts of Huatulco and Puerto Escondido in the state of Oaxaca have also been affected.
The current Foreign Office travel advice says: “Most of Mexico is occasionally subject to earthquakes. Tremors occur regularly, particularly in the states of Oaxaca and Guerrero.”
