The death toll from a fire at a daycare centre in northern Mexico rose to 35 children with another 40 or more hospitalized, many in extremely grave condition.

President Felipe Calderon has ordered an investigation into Friday's fire at the ABC daycare centre in the northern city of Hermosillo.

As flames blocked the centre's doorway, employees and neighbours used cars to punch holes through a wall and stumbled over unconscious infants and toddlers as they tried to rescue them.

Smoke inhalation killed many children, who ranged in age from a few months to about 3 years old, before rescuers could reach them, authorities say.

Injured children were being flown to the Shriners children's hospital in Sacramento, California, which specializes in burns.

Six adults were also hospitalized in Hermosillo.

More than 140 children were in the centre when the fire broke out.

It was unclear where or how the fire started, although it may have broken out in a nearby warehouse or a tire shop.