Eyewitnesses stopped in the street to stare at the sky as five giant white balls floated above a major city.
The bizarre phenomenon was caught on camera and has since been shared more than a million times as people search for an answer.
The clip of people watching the floating orbs above the Mexican capital of Mexico City shows people gathered on pavement staring up at the unexplained sight.
One eyewitness told the Mexican media: “There were five balls and they were moving, now they are moving around together.
“I have been here for 20 minutes and they are still there.”
So far there has been no official explanation for the white globes which most witnesses described as UFOs.
The video shows around 100 people looking up at the sky, many of them pointing at the mysterious balls of light.
One viewer Susana Carranco Galicia said: “They were white points seen in the sky that were moving and were making a triangle.”
While TmporalMnte Mueerto added: “They are white balloons, maybe they are bright because they are covered in silver which is very common at Christmas.
“If they were aliens, they would have destroyed the planet!”
Mexico City is one of the biggest cities in the world with a population of more than 23 million people.