HERMOSILLO, Mexico (AP) - Grieving parents buried their children Sunday after a devastating day care fire killed 40 infants and toddlers, stunning Mexico and prompting its president to promise a thorough investigation.

Funeral processions drove slowly to churches in the north-western city of Hermosillo decorated with balloons and flowers.

The family of two-year-old Maria Magdalena Millan dropped white roses on her casket and attached a Dora the Explorer balloon to the cross marking her grave at one of the first funerals held on Saturday.

"I love you and I don't want to leave you here!" her mother screamed.

President Felipe Calderon arrived in the city late Saturday. He wished surviving children a speedy recovery and promised families full government support and a thorough investigation into the fire's cause.

"I want to say to the mothers and fathers of the little ones who died that we share their profound sadness," Calderon said earlier in the day.

The death toll rose to 40 on Sunday after two children died in hospitals, according to Sonora state health secretary Raymundo Lopez Vucovich. Most of the victims had died of organ failure caused by smoke inhalation, he said.

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