The death toll from the massive explosion at Mexico's best-known fireworks market climbed to 32 on Wednesday as authorities worked to identify the dead and treat the dozens injured in the stunning incident.

Of the dead, 26 victims were found at the scene and six died at area hospitals, José Manzur, government secretary for the State of Mexico, said at a news conference Wednesday. Eighteen victims have yet to be identified, he said.

The explosion occurred at the open-air San Pablito market in Tultepec, in the State of Mexico. Officials said Wednesday that 59 people were wounded during the blasts, with 46 still in hospitals, five of them in grave condition.

PHOTOS: Mexicans Survey Devastation After Deadly Fireworks Explosion

Fundación Michou y Mau, a Mexico City children's charity, told NBC News that it was trying to transfer a 13-year-old boy named Juan Carlos, who it said had suffered burns over 35 percent of his body.

Roberto López, the charity's director general, told NBC station KPRC of Houston that the organization eventually hopes to send as many as eight children to the United States.

"We're still locating people," he said.

Video of the blast showed an arsenal of fireworks exploding at the market and a massive plume of smoke enveloping the area, just outside Mexico City. Officials have not yet given a cause for the explosions.

A 12-year-old witness, Yahir David Sanchez Ortega, said he was outside and going to buy something when the first stand began to explode and "all the bricks from the fireworks market started flying."

Yahir said he saw people "running with blood on their heads" and screaming for help.

"Everything was exploding until you went deaf, where you couldn't hear all the noise," he said. "I felt like the roof was going to cave and crush my head."

"I thought I was going to die," he said.

Another witness, Juan Carlos Saldaña, told NBC News on Wednesday that he was still waiting for news on three relatives who have been missing since the explosions.

"We feel devastated, with hope of still finding them," he said.

Saldaña said he and his family have not been able to rest as they await word. In addition to his three missing relatives, two other relatives are hospitalized, he said.

Saldaña described running to try to help people who were inside the market as the explosions began.

"I went in to look for my family," he said.

Mexico has a history of fireworks explosions in market areas, including two previous explosions in Tultepec. At least 62 people were killed in the La Merced market in Mexico City in one of the incidents, on Dec. 12, 1988.