(CNN) -- Four children are among the seven deaths confirmed so far after a natural gas explosion rocked a maternity hospital on the outskirts of Mexico City on Thursday morning.
There are fears that more babies and adults may be trapped in the debris of the hospital, which was on the verge of collapsing after the explosion, according to government and emergency officials.
More than 50 were injured, including 22 children, Mexico City Mayor Miguel Angel Mancera said. An unknown number of people are trapped.
A truck was supplying natural gas to the hospital when apparently a hose burst and the resulting leak caused an explosion, Mancera said.
At least eight people were seriously injured, he said.
The Red Cross reported that it provided 23 ambulances and more than 40 rescuers to the efforts. The agency said it transported nine babies to area hospitals.
Many others were being treated for cuts from flying glass after the blast, he said.
The Cuajimalpa Maternal Hospital is located on the southwest outskirts of Mexico City. It was founded in 1993 and is part of the city’s government health system.
Photos from the scene show that the gas truck belongs to Gas Express Nieto, a natural gas provider among the four biggest gas distributors in Mexico, according to the company.
Gas Express did not immediately comment on the explosion. Its Twitter account is private and its Facebook page appeared to have been taken offline.
One of the city’s publicly accessible webcams captured the blast, showing a plume of smoke rising from the direction of the hospital.
Some witnesses reported seeing a fire burning at the hospital. Mancera said it was a controlled fire designed to burn off the leaking gas from the delivery truck.
CNN’s Krupskaia Alis contributed to this report from Mexico City. CNN’s Eliott McLaughlin and Mayra Cuevas contributed from Atlanta.
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