A backhoe grumbles under its load of debris.
A woman calls on a megaphone for the family of a missing child.
Hundreds of volunteers dish out food and water to tired rescue workers.
Then, suddenly, an eerie silence.
People clench their fists and hold them in the air — a signal for others to be quiet.
It gives rescue workers a chance to listen for signs of life, as they pore over the rubble of the Enrique Rebsamen Elementary School nearby.
Before long a whistle blows, a generator hums, and people start moving frantically once again.
This scene repeats itself again and again throughout the day.
With a blue paper mask hanging under his chin Miguel Villegas watches on.
He is a rescue worker and says he believes there are two girls still alive trapped inside. I asked him what made him think they were alive.
"For the screams that we heard," he said.
"They started to scream. It had started to rain, I think they were drowning with the mud of the debris and one of the girls screamed and the other girl stuck her hand out."
He raises his own hand and clarifies, "she stuck out her little hand".
At least 20 children were killed when the building collapsed and Miguel says some bodies are still stuck in the rubble.
"Horrible, horrible," he said when asked what it is like being in there.
"It is something indescribable. My heart and soul can't comprehend this. To be in a place that is so terrible, so disheartening with anguish, sadness, death — it is indescribable," he said.
Nearby stands Edgar Sanchez, another rescue volunteer. He too looks exhausted, but has vowed to stay on.
"Hope dies last," he said.
"We are going to be there trying and hoping until the very end."
He pauses when silence is called for once again.
Eventually, a truck starts, a whistle blows and the volunteers race around once again.
Few stop to notice two lists written in marker pen and stuck to the wall of a building.
One is of survivors who have been taken to hospital.
The other bears the names of the "fallecidos" — the deceased.
A Mexican Navy official later confirmed all the pupils of the school had been accounted for, either alive or dead.
A total of 11 children were rescued, while 19 children and six adults had died.
One adult survivor is still awaiting rescue from the rubble.