Steph Solis and Mike James

USA TODAY

At least 29 people died and 50 others were injured after an explosion ripped through a popular fireworks market in Mexico, sending a massive plume of smoke into the sky as 10 Red Cross ambulances rushed to the scene.

The governor of the State of Mexico, Eruviel Avila, said dozens were killed in the explosion that sent flames through the pyrotechnics booths at the open-air San Pablito Market in Tultepec, about 20 miles north of Mexico City. At the time of the blast, the market was packed with shoppers buying fireworks for upcoming holiday celebrations.

The cause of the explosion, which is not being linked to terrorism, wasn't immediately known.

"Mexico is in mourning," Avila said in an interview with Foro TV.

Mexican President Enrique Peña Nieto took to Twitter to offer his condolences to the families of those who lost their lives in the blast and wish the injured a speedy recovery.

Sirens wailed and a heavy scent of gunpowder lingered in the air after the afternoon blast at the market, where most of the fireworks stalls were completely leveled. The smoking, burned out shells of vehicles ringed the perimeter, and first responders and concerned local residents combed through the ashes. Firefighters hosed down still-smoldering hotspots.

The Mexican Red Cross said it sent 10 ambulances with 50 paramedics.

Crescencia Francisco Garcia arrived in the afternoon to buy fireworks and said she was near the middle of the grid of stalls when the explosions began around 2:30 p.m.

"All of a sudden it started booming," the 41-year-old Mexico City resident said. "I and the others surrounding me all took off running."

Cesar Ornelas of Atizapan de Zaragoza was only 10 minutes into shopping with his son and his father when he heard the first explosions. He tried to run, but something knocked him to the ground from behind. He tried several times to get up, unsuccessfully, and ultimately his 15-year-old son Francisco had to drag him out.

"We didn't look back," said Ornelas, who suffered light burns and a large bruise over his left kidney. His white tank top had a fist-size burn on the chest. "We heard how the explosion was kind of going off bit by bit."

In 2005, a fire engulfed the same market, touching off a chain of explosions that leveled hundreds of stalls just ahead of Mexico's Independence Day. A similar fire at the San Pablito Market also destroyed hundreds of stands in September 2006.

Many in Mexico traditionally celebrate holidays — including Christmas and New Year's — by setting off noisy firecrackers and rockets.

Well after the blast, first responders continued to try and put out hotspots and fireworks continued to go off. National Civil Protection Coordinator Luis Felipe said there was no choice but to let any unexploded fireworks be consumed.

The scene remained dangerous with some nearby homes damaged from the blast, Puente added. He asked people to stay at least 3 miles away from the scene to avoid hindering the emergency response.

Contributing: The Associated Press.