The death toll for the 7.1-magnitude earthquake which hit Mexico has been raised to 230 – as rescuers desperately work to rescue a young girl trapped alive in the rubble of a collapsed school.

The number of confirmed dead in Mexico City rose to 100 as the nation’s capital bore the brunt of the deaths and damage in Tuesday’s quake.

The girl was found by rescuers in the debris at the Enrique Rebsamen school in a southern area of the capital.

(PA Graphics)(PA Graphics)

Foro TV reported that rescuers spotted the child and shouted to her to move her hand if she could hear them, which she did. A search dog subsequently entered the wreckage and confirmed she was alive.

Hours later the crews were still working to free her, as images of the rescue effort were broadcast on TV screens nationwide.

Workers in neon vests and helmets used ropes, pry-bars and other tools, frequently calling on the anxious parents and others gathered around to be silent while they listened for any other voices from beneath the school.

At one point, the workers lowered a sensitive microphone inside the rubble to scan for any noise or movement. A rescuer said they thought they had located someone, but it wasn’t clear who.

“It would appear they are continuing to find children,” said Carlos Licona, a burly sledge-hammer wielding volunteer who came to help in any way he could. Asked if that made him optimistic, he said, “I hope so.”

It was part of similar efforts at the scenes of dozens of collapsed buildings, where firefighters, police, soldiers and civilians wore themselves out hammering, shoveling, pushing and pulling debris aside to try to reach the living and the dead.

By mid-afternoon, 52 people had been pulled out alive since the quake, Mexico City’s Social Development Department said, adding in a tweet: “We won’t stop.”

Among them were 11 people rescued at the Enrique Rebsamen school, where three people remained missing, two children and an adult. Earlier, journalists saw rescuers pull two small bodies from the rubble, covered in sheets.

More than 24 hours after the collapse, the debris being removed from the school began to change as crews worked their way inside: from huge chunks of brick and concrete, to pieces of wood that looked like remnants of desks, to a final load that contained half a dozen sparkly hula-hoops.

A man walks through a door frame of a building that collapsed in Mexico City A man walks through a door frame of a building that collapsed in Mexico City (Marco Ugarte/AP)

A volunteer rescue worker, Dr Pedro Serrano, managed to crawl into the crevices of the tottering pile of rubble and make it to a classroom, where he found no survivors.

“We saw some chairs and wooden tables. The next thing we saw was a leg, and then we started to move rubble and we found a girl and two adults — a woman and a man,” he said. All were dead.

“We can hear small noises, but we don’t know if they’re coming from … the walls above, or someone below calling for help,” he added.

A helicopter overflight of some of the worst-hit buildings revealed the extent of the damage wrought by the quake: three mid-rise apartment buildings on the same street pancaked and toppled in one Mexico City neighbourhood; dozens of streets in the town of Jojutla, in Morelos state, where nearly every home was flattened or severely damaged and a ruined church where 12 people died inside.

Men carrying beams of wood offer their services at a site of earthquake damage in in Mexico CityMen carrying beams of wood offer their services at a site of quake damage in Mexico City (Rebecca Blackwell/AP)

The death toll included 100 people killed in Mexico City, 69 in Morelos state just south of the capital and 43 in Puebla state to the south-east, where the quake was centered. The rest were in Mexico State, according to the official Twitter feed of civil defence agency head Luis Felipe Puente.

President Enrique Pena Nieto declared three days of national mourning even as authorities made rescuing the trapped and treating the wounded their priority. “Every minute counts to save lives,” Pena Nieto tweeted.