Desperate rescue operations underway after devastating Mexico quake

Volunteers and rescue workers have raced to help those trapped by toppled buildings, after a devastating earthquake struck Mexico.

At least 216 people have been killed in the magnitude 7.1 quake which jolted central Mexico on Tuesday (local time), with the death toll expected to rise as the search for survivors continues. An earlier death toll of 248 was later revised down.

The disaster has drawn residents together, as their lives come apart. Thousands fled into the streets when shaking began shortly after a pre-planned earthquake drill and hundreds leapt into action as emergency workers.

Swarms of people have been seen gathering around and on top of collapsed buildings, handing off buckets filled with rubble, while trying to find those trapped.

At one site in Mexico City, where at least 44 buildings collapsed, rescuers standing on top of wreckage were seen calling for silence as they listened for survivors stuck below.

At another, resident Alma Gonzalez was trapped in her apartment after the ground floor collapsed.

"The people in the house next door helped me get out with a ladder," she told Associated Press.

"I am just grateful to God that we are here for something."

But not all were able to escape and the witnesses have been left shell-shocked.

"Unfortunately, I saw [the building] collapse, thinking there are children inside," said resident Juan Chanes Mora.

"It was regrettable and the way it collapsed was very shocking."

In the wake of the tragedy, Mexican President Enrique Pena Nieto has ordered all hospitals to open their doors to the injured.