Seventy people were injured in the incident that took place on Tuesday in Tultepec, about 40 km north of Mexico City, said Eruviel Avila, governor of the State of Mexico.
Avila said at a press conference that 26 people died at the scene of the incident and that three others later died in hospitals where the wounded are being treated, Efe news reported.
The incident occurred just before 3 p.m., at the San Pablito fireworks market, where Civil Protection, fire department and federal agents are now working to extinguish the blaze and rescue victims.
Avila said that three children who have suffered serious burns will be transferred to a hospital in Texas, US.
He added that the Attorney General of Mexico will investigate the case as it is related to Mexico’s Federal Law on Firearms and Explosives.
Tultepec Civil Protection radio operator Antonio Escalona told Efe news that currently “more than 20 or 25 units throughout the State of Mexico, the Federal Government and the Army” have been dispatched to help victims.
“They all have fractures, bruises, burns, but none of them suffers serious injury,” he said.
In addition, the Red Cross has deployed 20 ambulances with approximately 70 paramedics.
Mexican President Enrique Pena Nieto expressed his condolences “to the relatives of those who lost their lives in this accident” as well as his “wishes for a speedy recovery for the injured.”