Local residents watched in horror as a multi-storey apartment block in the centre of Mexico City began to shake before imploding into a cloud of dust.
It was one of dozens of buildings that crumbled to the ground as the powerful magnitude-7.1 earthquake hit central Mexico shortly after 1pm local time.
One building even exploded and caught alight.
Thousands of people rushed out of their apartments in panic and poured onto the streets.
Workers evacuated buildings when sirens sounded as offices shook with terrifying force.
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"Horrible, horrible, frighteningly horrible. Frighteningly horrible. I think, for me it topped, it surpassed the violence from the earthquake last Thursday night."
"Oh my god. This is a bad idea to be on this boat. Woah."
In southern Mexico, tourists who were enjoying a boat ride were instead fearing for their lives as the river's water shook uncontrollably.
The usually busy international aiport in Puebla was forced to shut operation for about three hours and flights were suspended.
It was the second powerful earthquake to hit Mexico this month after 98 people were killed from a quake two weeks ago.
The earthquake also struck on the 32nd anniversary of another disaster - the 1985 quake that killed as many as 10,000 people in Mexico.
Reporter Manuel Rueda who was in Mexico City told CBS, just hours before the quake hit, the city was in fact holding an earthquake drill.
"Ironically there was an earthquake drill this morning which happens every September in Mexico City. They do this earthquake drill on the anniversary on the 1985 earthquake. Today September 19 was the anniversary of the earthquakethat killed hundreds of people in Mexico City so they do these drills so there was actually people going outside today and doing the same thing and then in the afternoon it was for real."s
Mexico City is one of the most densely populated areas on Earth.
More than 20 million people live in the metropolitan area.
Rescue teams are now frantically searching through the mounds of rubble for survivors.
There are concerns about aftershocks - guards are blocking people from entering offices and shopping malls until the buildings are deemed safe.
