HERMOSILLO: Grieving parents began burying their children after a devastating day-care fire killed 38 infants and toddlers in a tragedy that has stunned the nation and prompted Mexico's president to promise a thorough investigation.

The family of 2-year-old Maria Magdalena Millan dropped white roses onto her casket and attached a Dora the Explorer balloon to the cross marking her grave during one of the first funerals held Saturday.

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

President Felipe Calderon arrived in the northwestern Mexican city late Saturday to console the injured. He wished children a speedy recovery and promised families full support for their needs from his health ministry and a thorough investigation into the cause of a tragedy that he said was felt by all Mexicans.

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

The death toll rose to 38 Saturday after three more children died in hospitals, according to Sonora state health secretary Raymundo Lopez Vucovich. Most of the victims had died of organ collapse caused by smoke inhalation, he said.

Delfina Ruelas, 60, said her grandchild German Leon died of his burns Saturday, three days after his fourth birthday and a day after the raging fire from an adjoining tire and car warehouse spread to the roof of the day care and sent flames raining down on the young children.

Fire officials still don't know how it started.

Ruelas and her husband saw television news reports that the ABC day care was ablaze Friday and rushed over.

"I thought he wasn't that burned and that we would find him OK, but he was very burned," said Ruelas, dissolving into tears outside the morgue in the northern city of Hermosillo, where she waited along with 30 other relatives. "They operated on him yesterday, and he held on, but today he couldn't hold on."

Firefighters carried injured children through the front door — the building's only working exit — and through large holes that a civilian knocked into the walls before rescue crews arrived, according to a fire department official who spoke on condition of anonymity because he was not authorized to speak publicly about the fire.

Noe Velasquez, an employee at a nearby auto parts store who helped pull out five toddlers, said the father of one of the children rammed his pickup truck through a wall. Velasquez did not know if the man's child survived.

The tragedy in Hermosillo, capital of the state of Sonora with a population of about 560,000, again raised questions about building safety in Mexico. Officials cracked down on code violations last year following a deadly stampede at a nightclub that killed 12 and a disco fire nine years ago that killed 21. Both clubs were in Mexico City.

There were an estimated 142 children in the day care at the time of the fire, their ages ranging from 6 months to 5 years, and six staffers to look after them, Sonora state Gov. Eduardo Bours said at a news conference.

The ratio is in keeping with legal standards, said Daniel Karam, the director of Mexico's Social Security Institute, which outsourced services to the privately run day care.

A May 26 inspection found that the day care building — a converted warehouse with a few windows mounted high up — complied with safety standards, Karam added.

Asked if the single functioning exit constituted a safety code violation, Karam only repeated that the building had passed the inspection, although he conceded that the security requirements might have to be re-evaluated.

"We always have to be open to improvements, especially when we have a tragedy that has so moved us," Karam said.

Guadalupe Arvizu, who was visiting her injured 2-year-old grandson at a hospital, said the building has an emergency exit but it could not be opened on the day of the fire. She did not know why.

"The place is in bad condition. It's a warehouse. There are no windows in the classrooms," said Arvizu, whose daughter — the boy's mother — is a caretaker at the day care but was not injured in the fire.

Some of the children had third-degree burns, the Hermosillo fire department official said.

"As a doctor I have confronted death on many occasions," said Lopez, the state health secretary, his voice cracking. "But I'm seeing so much misfortune and suffering now, it breaks my heart."

Thirty-three children remain hospitalized, 23 of them in Hermosillo, including 15 who are in critical condition, Lopez said. One of them is brain dead.

Nine children were transferred to other Mexican hospitals, eight of them to the western Mexican city of Guadalajara that has a special burn unit, and one to Ciudad Obregon in Sonora, he said.

A 3-year-old girl with burns over 80 percent of her body was sent by military transport to Shriners Hospital for Children Northern California, said Carlos Gonzalez Gutierrez, Consul General for Mexico based in Sacramento, California.

The girl's injuries could require months of treatment, which will be free of charge, Gonzalez Gutierrez said. One parent is traveling with the girl, and will be housed nearby.

"It's going to be challenging. The survivability is about 50 percent. A lot of it is how deep the burn is and where it's located and how bad is the smoke inhalation," said Dr. Tina Palmieri, assistant chief of burns for Shriners'.

Four children were released from the hospital, along with two of six adults who had been admitted, Lopez said. The hospitalized adults included five of six women who took care of the children at the center, plus a security guard. The four still hospitalized are in stable condition, Lopez said.

Lopez encouraged citizens to donate blood because he said many of the children are going to need it.

Firefighters took two hours to control the blaze. Police trucks cordoned off the block surrounding the cavernous salmon-and-blue day care, while forensic investigators gathered material, searching for clues to what started the blaze.

Velasquez said he and several other people rushed to the day care when they saw smoke. Teachers already had lined up some of the children outside but the very smallest were trapped inside, some of them in their cribs. Velasquez said he pulled out limp toddlers without knowing if they were dead or alive.

"I didn't sleep last night," he said. "I've never gone through anything like that in all my life."