A powerful earthquake has been felt in Mexico's capital, shaking buildings and sending people running into the street.
The magnitude 7.2 quake was centred in the western state of Guerrero, north of the beach resort of Acapulco.
Its centre was 165 miles south west of the capital, the US Geological Survey said.
The quake shook Mexico City for at least 30 seconds, with some walls cracking and crumbling, but there were no reports of major damage or casualties.
Journalist James Blears, based near Mexico City, told Sky News: "This earthquake had tremendous power - it lasted 30 seconds, instead of just a few seconds.
"Buildings were swaying and thousands of people have evacuated buildings and are standing in the street."
Mexico City Mayor Miguel Angel Mancera said on Twitter that authorities were checking the sprawling capital for damage.
"For now we are only seeing evacuations," Mr Mancera said.
Luis Felipe Puente, head of the Mexican government's emergency services, said on Twitter there were no immediate reports of damage.
The US Pacific Warning Centre said it did not expect the quake to trigger a destructive tsunami.
Nevertheless, residents of the capital were shaken by the quake, one of the biggest to hit Mexico in several years.
"I had to hold on to a tree, like a drunk," said Pedro Hernandez, 68, a doorman working in central Mexico City.
"This is really strong," said Gabriel Alejandro Hernandez Chavez, 45, an apartment building guard in central Mexico City.
"And I'm accustomed to earthquakes."
Mexico City is vulnerable to earthquakes because much of it sits atop the muddy sediments of drained lake beds that quiver as quake waves hit.
The magnitude 8.1 quake in 1985 that killed at least 6,000 people and destroyed many buildings in Mexico City was centred 250 miles (400 kilometers) away on the Pacific Coast.