A 7.1 magnitude earthquake has hit central Mexico, the US Geological Survey has said, on the anniversary of a 1985 quake that caused major damage, and 11 days after a huge temblor killed 96 people.
It said the epicentre was near the town of Raboso, about 76 miles south east of Mexico City.
Mexico’s seismological agency calculated its preliminary magnitude at 6.8 and said its centre was east of the city in the state of Puebla.
Earlier in the day buildings across the city held preparation drills on the anniversary of the 1985 quake.
National Civil Protection chief Luis Felipe Puente tweeted that there were no reports of damage so far, but thousands fled office buildings along the central Reforma Avenue as alarms blared, and traffic stopped around the Angel of Independence monument.
In Mexico City pictures fell from walls, objects were shaken off of flat surfaces and computer monitors toppled over. Some people dived for cover under desks.
Much of Mexico City is built on former lakebed, and the soil is known to amplify the effects of earthquakes even hundreds of miles away.
Local television stations broadcast images of collapsed facades and streets filled with rubble.
There were no immediate reports of casualties.