MEXICO CITY — A huge explosion at Mexico’s largest fireworks market on Tuesday afternoon killed at least 27 people and injured 70, the Mexico State police said.

The explosion occurred at about 3 p.m. at the well-known San Pablito fireworks market in Tultepec, a town on the outskirts of Mexico City. A video of the episode captured by a passing driver showed a chain reaction of explosions followed by enormous plumes of smoke.

Dozens of ambulances and fire trucks rushed to the site. Warning that the area had not been secured, officials asked people to stay away out of concern that there could be more explosions. Rescue workers continued to search the scene for victims.

Fireworks accidents are not uncommon in Mexico, especially during the Christmas season, when families purchase hundreds of fireworks for the holidays. Fireworks are a favored tradition among Mexicans, and markets are filled with small fireworks for children.