Mexico blast: Nine baby survivors undergo DNA tests Published duration 31 January 2015

image copyright Reuters image caption A nurse and two babies were killed in the gas explosion

Nine babies found alive in the rubble of a Mexican children's hospital after a gas blast have undergone DNA tests to help reunite them with their parents.

The testing was necessary as the babies were not wearing identity bracelets, Mexico City Mayor Angel Mancera said.

The explosion on Thursday killed a nurse and two infants and injured more than 70 others.

It is believed to have been caused by a leak in a hose from a gas lorry fuelling the hospital's tanks.

"There are parents who have identified their children, but as the babies did not have bracelets on, we have to follow a protocol to identify them," Mr Mancera was quoted by Reuters as saying.

Tank workers struggled for about 15 minutes to repair the hose while a large gas cloud formed, witnesses said.

image copyright AFP image caption The explosion is thought to have been caused by a leaking hose from a gas tank

image copyright Reuters image caption Thousands of tonnes of rubble needs to be cleared after the blast

The explosion shot a fireball into the sky, and was so powerful that much of the building collapsed.

Mothers inside shielded their infants to protect them for the blast. Many of those injured suffered burns or cuts from broken glass.

Rescuers searched under rubble and twisted metal but by late on Thursday said no one was still trapped.

Mr Mancera said a bigger tragedy was avoided as the hospital was able to evacuate many of the people inside before the leak turned into an explosion.

The three operators of the gas lorry have been detained.

There have been a number of other fatal gas explosions in Mexico over recent years.

image copyright Reuters image caption The "super explosion", as one witness put it, was so big much of the hospital collapsed