A volcano spectacularly shot ash 3,000 metres into the air in an eruption that shook buildings nearly 40 miles away.
For a third time in a week lava-like fireballs flew out over the slopes of Mexico's Popocatepetl volcano, the country's second highest peak.
The eruption created a 3,000 metre ash column and could be felt in the state capital city of Puebla 37 miles away.
The explosion prompted local authorities to issue public health warnings to nearby residents, urging them to flee if they lived within 7.5 miles of the volcano.
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Residents were also advised to stay indoors, seal water tanks to avoid ash contamination and, if they did need to go out, cover their eyes, nose and mouth with a wet handkerchief.
The National Coordination of Civil Protection said the eruption had shot flaming fragments over an area of 1.2miles, causing fires in the nearby hills of Nexpayantla and Tenenepanco.
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Gustavo Salvatori, director of the Civil Protection in the city of Puebla, said on Twitter that there was a possibility of ash falling on the city.
David Eduardo Leon Romero, the national coordinator of Civil Protection, said Popocatepetl, which is considered one of the 10 most dangerous volcanoes in the world, was being monitored 24/7.
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Experts at the University of Manchester noted that volcanic activity at Popocatepetl had increased in the last two weeks.
About 25 million people live within about 60 miles of the active volcano's crater.
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Popocatepetl, which means 'mountain the smokes' in the traditional Nahuatl language, is the second highest peak in Mexico at 5,452 metres (17,887 feet).
It straddles the states of Puebla and Morelos in central Mexico, lies 56 miles from the national capital, Mexico City, from where it can be seen on a clear day.
