Seven children died in a pre-dawn fire on Friday in Iztapalapa, a populous town within Mexico City's greater metropolitan area, Xinhua reports.
The fire broke out just before 5 a.m. local time (11:00 GMT) at a cardboard-and-sheet metal shack tucked between cement homes in the neighborhood of Buenavista.
The victims were children aged 2 to 13, including five siblings and a cousin as well as their minor caregiver, and all of their bodies have been found by firefighters, according to Iztapalapa prosecutor Jose Antonio Escobar.
The parents were reportedly out working at the time.
The cause of the blaze remained under investigation.
One local TV news reporter speculated the occupants may have been trying to keep warm beside a fire that got out of control.
Iztapalapa Mayor Clara Brugada said her government will launch a campaign to warn residents about the hazards of using gas to heat homes this time of year, when temperatures plunge during the night.