A large part of the building was destroyed in the explosion. Several babies were found alive among the debris.
Rescue personnel were searching for survivors among the rubble. Dozens of women and children were rescued from the site, some with injuries caused by glass.
Some of the injured were evacuated with the help of helicopter.
The explosion is believed to have been caused by a leak in a hose from the truck that was filling the hospital's tanks.
President Enrique Pena Nieto expressed solidarity with the families of the victims on Twitter.