A powerful chain-reaction explosion ripped through Mexico's best-known fireworks market killing at least 29 people and leaving dozens more badly burned.
The San Pablito fireworks market on the outskirts of Mexico City was especially well stocked for the Christmas holidays and bustling with hundreds of shoppers when it was hit by the third serious blast in 11 years.
Tuesday afternoon's explosion sent up a towering plume of smoke that was lit up by a staccato of bangs and flashes of light. Once the smoke cleared, the open-air bazaar was reduced to a stark expanse of ash, rubble and the charred metal of fireworks stands, casting a pall over the country's Christmas season.
Mexico State health officials said 72 people were being treated for injuries from the explosion, including for severe burns, in some cases over 90% of their bodies. Ten children were among those in hospital.
The authorities have not yet said what may have caused the explosions which took place in Mexico State, which rings the country's capital.
Survivor Crescencia Francisco Garcia said she was in the middle of the grid of stalls when the thunderous explosions began. She froze, reflexively looked up at the sky and then took off running through the smoke once she realised everyone was doing so. As she ran she saw people with burns and cuts, and lots of blood.
"Everything was catching fire. Everything was exploding," she said. "The stones were flying, pieces of brick, everything was flying."
Mexico State Governor Eruviel Avila said that in addition to the 26 people who were killed at the market, three more victims died later in hospital.
"We are going to identify who is responsible," he said.
Sirens wailed and a heavy scent of gunpowder lingered in the air well after the thunderous explosions at the market, which were widely seen in a dramatic video.
The smoking, burned-out shells of vehicles ringed the perimeter, and first responders and local residents wearing blue masks over their mouths combed through the ash and debris. Firefighters hosed down still-smouldering hotspots.
Tultepec Mayor Armando Portuguez Fuentes said the market was especially well stocked because demand for noisy firecrackers and rockets increases at this time of year.
"We are obviously in the high season," he said. "There was more product than usual because we are a few days away from Christmas, a few days away from New Year's, and those are the days when the products made here are consumed the most."
He said the manufacture and sale of fireworks is a key part of the local economy. He added that it is regulated by law and under the "constant supervision" of the defence department, which oversees firearms and explosives.
"This is part of the activity of our town. It is what gives us identity," he said. "We know it is high-risk, we regret this greatly, but unfortunately many people's livelihoods depend on this activity."
"My condolences to the families of those who lost their lives in this accident and my wishes for a quick recovery for the injured," President Enrique Pena Nieto said via Twitter.
A fire engulfed the San Pablito Market in 2005, touching off a chain of explosions that levelled hundreds of stalls just ahead of Mexico's Independence Day. A year later a similar incident at the same market also destroyed hundreds of stands.
Deadly fireworks explosions have occurred with some regularity in Mexico, including in 2002, when a blast at a market in the Gulf coast city of Veracruz killed 29 people.
In 1999, 63 people died when an explosion of illegally stored fireworks destroyed part of the city of Celaya, and in 1988, a fireworks blast in Mexico City's La Merced market killed at least 68.