A powerful chain-reaction explosion has ripped through Mexico's best-known fireworks market on the northern outskirts of the capital
At least 31 people have been killed and dozens more have been injured while the market has become a charred wasteland.
Video of Tuesday's blast showed a dramatic staccato of rockets exploding in flashes of light, levelling the open-air San Pablito Market in Tultepec as it bustled with shoppers stocking up on fireworks to celebrate Christmas and the New Year.
Some children suffered burns to more than 90 percent of their bodies and were being sent to the US city of Galveston in Texas for treatment, said Eruviel Avila, the state governor.
He also vowed to find and punish those responsible and to provide economic assistance to those who had lost their livelihoods.
Vendors' stands were reduced to piles of rubble, ash, and charred metal. It was the third devastating explosion and fire to ravage the market since 2005.
Crescencia Francisco Garcia said she was in the middle of the grid of stalls along with a few hundred others when the thunderous explosions began. She froze, 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," Ms Francisco said. "The stones were flying, pieces of brick, everything was flying."
The federal attorney general's office opened an investigation, saying in a statement that six separate blasts caused the destruction.
Isidro Sanchez, the head of Tultepec emergency services, said earlier that a lack of safety measures was the likely cause of the blasts.
The federal police said a forensic team had been sent to investigate and that at least 70 people had been injured. Videos from the scene showed people frantically fleeing, while aerial footage revealed blackened stalls and a flattened tangle of metal and wood.
The state's top prosecutor raised the death toll late on Tuesday to 31, most of whom died at the market.
More than 80 percent of the 300 stalls at the market were destroyed by the explosions.
He said the market was inspected by safety officials last month and no irregularities were found.
Mexican media reported there were 300 tonnes of fireworks at the market at the time of the explosions.
Tultepec Mayor Armando Portuguez Fuentes said the market was especially well stocked because demand for noisy firecrackers and rockets soars this time of year.
"We are obviously in the high season," Mr Portuguez 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."
A similar fire engulfed the San Pablito Market in 2005, touching off a chain of explosions that leveled 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.
AP / Reuters