At least 25 children and five employees were hospitalized after Friday's fire in ABC day care in the city of Hermosillo, said Jose Larrinaga, a spokesman for investigators in the state of Sonora, which borders Arizona.
Some of the injured suffered severe burns and might be taken to U.S. hospitals, Sonora Gov. Eduardo Bours said.
"For now, we're concentrating on saving as many kids as possible," he said.
There were about 100 children in the day care at the time, with ages ranging from six months to 5 years, said Guadalupe Ayala, coordinator of Red Cross rescue workers.
"Firefighters had to knock holes in the walls to get the children," he said.
The fire may have started at a tire and car warehouse Friday afternoon and spread to the neighboring day care center, state officials said. Firefighters took two hours to control the blaze, the cause of which was still unknown.
Larrinaga said most children died of asphyxiation.
Neighbors rushed to help pull out the children as screaming preschool teachers ran through thick clouds of black smoke, Reforma newspaper reported.
Sobbing parents flooded hospitals, desperate for news about their children.
