A nurse and a child died after the blast, which destroyed around 70 percent of the hospital, Mexico City Mayor Miguel Angel Mancera said.
Speaking on national television, Mexico City’s health minister said another child had died and more than 70 people were injured.
Several babies were found under the rubble. Scores of rescue workers dug through the concrete and twisted metal for survivors.
People seeking information on family members gathered around police lines that were set up to keep bystanders away from the chaotic scene earlier in the day. Some of the injured were evacuated by helicopter, and aerial footage showed firefighters scrambling over the skeletal wreckage of the building.
“I am so worried about my sister. She’s supposed to have given birth. We brought her in yesterday,” said Monserrat Garduno, a 32-year-old nurse. “They won’t let us pass. I want to know how she is.”
Ambulances were at the scene to treat survivors. Around 100 people were in the hospital at the time of the explosion, according to a city official.
A leak in a hose from the truck, which was fueling the hospital’s tanks, was believed to have triggered the explosion, officials said.
“They tried to stop the leak, but it was not possible,” Mancera said. Three people had been detained and two had been hospitalized, he added.
Many areas of Mexico City have no mains gas supply, and rely on deliveries from gas trucks. Mancera said the gas truck company involved had been working in Mexico City since 2007.
President Enrique Pena Nieto gave his condolences on Twitter, while Pope Francis urged his Twitter followers to pray for the victims and their families. (Reuters)