Mexico was struck by a powerful earthquake on Tuesday that killed at least 217 people and toppled several buildings in the capital.

The death toll was slightly reduced, after it climbed throughout the night as rescue workers continued digging through rubble, with 21 children at a collapsed primary school among those killed. 

The 7.1 magnitude earthquake came on the anniversary of a devastating 1985 temblor that caused major damage to Mexico City, and struck as many people took part in an earthquake drill.

Mexico City's buildings crumble as deadly 7.1 magnitude earthquake hits - in pictures

It also came less than two weeks after another major quake killed 90 people in the country's south.

Thousands fled into the streets in panic as the powerful quake rocked several states in the centre of the country.

The epicentre was Atencingo in Puebla state, around 75 miles south-east of Mexico City, and struck at a depth of 32 miles, according to the US Geological Survey, at 1.14pm local time.

Mexico City faces bulk of the destruction

Forty three of the deaths were in the state of Puebla, some 75 miles east of Mexico City, where the earthquake struck, while 71 people were killed in Morelos, to the south of the capital. 

But it was Mexico City itself that was hardest hit, with 86 confirmed dead, according to Luis Felipe Puente, national coordinator of the Civil Protection service. 

Much of the region was plunged into darkness, with forty percent of Mexico City and 60 percent of the state of Morelos still without electricity early on Tuesday.

President Enrique Pena Nieto urged people to stay in their homes if it was safe to do so and keep the streets free of congestion to allow emergency vehicles to pass.

"This earthquake is a hard and very painful test for our country," he said in a message to the nation. "Us Mexicans have had difficult experiences as a consequence of earthquakes in the past. And we have learned to respond to these episodes with commitment and the spirit of solidarity."

He added: "We will stay united, confronting this new challenge together."

People trapped in rubble

Tony Gali, the governor of Puebla, said that church steeples had been toppled in the city of Cholula.

Mayor Miguel Angel Mancera said buildings fell at 44 places in Mexico City, where more than 50 people died, and fires broke out in several of them. 

Interior Secretary Miguel Angel Osorio Chong said rescue teams were working painstakingly with picks and shovels to free people who had been trapped

"We have some buildings where we have reports that there could be people inside. They are doing it with lots of caution," the interior secretary said, adding that more rescue personnel would be needed.

At one site, reporters saw onlookers cheer as a woman was pulled from the rubble. Rescuers immediately called for silence so they could listen for others who might be trapped.

One video posted on social media showed a large industrial building swaying and then crumbling in a huge cloud of dust and rubble. Mexican TV showed cars crushed by debris.

Magnitude 7.1 Earthquake in Mexico

There was chaos in Mexico City, with traffic jammed to a standstill and ambulances trying to reach those injured.

Hundreds of civilians rushed to help search for people who may have been trapped.

'There was thunder...then dust'

Carlos Mendoza, 30, said that he and other volunteers in Mexico City had been able to pull two people alive from the ruins of a collapsed apartment building after three hours of effort.

"We saw this and came to help," he said. "It's ugly, very ugly."

Another volunteer rescue worker, Mariana Morales, said she saw a building collapsing in a cloud of dust before her eyes as she travelled in a taxi.

"There was the sound of thunder ... then dust and all this," she said. "The people are organising quickly."

Gala Dluzhynska was taking a class with 11 other women on the second floor of a building on trendy Alvaro Obregon street when the quake struck and window and ceiling panels fell as the building began to tear apart.

She said she fell in the stairs and people began to walk over her, before someone finally pulled her up.

On Twitter, relatives posted pleas for news of family members, including 8-year-old Alexis Vargas Macias who was at Enrique Rebsamen school when the quake hit.

Hours after the quake, rescue workers were still clawing through the wreckage of the primary school looking for any children who might be trapped. Some relatives said they had received Whatsapp message from two girls inside.

President Enrique Pena Nieto visited the school late on Tuesday and said 22 bodies had been recovered there, two of them adults.

He added in comments broadcast online by Financiero TV that 30 children and eight adults were still reported missing. Rescuers were continuing their search and pausing to listen for voices from the rubble.

City joins together in rescue efforts

Hours after a school collapsed, killing at least 20 children, people were still searching through the rubble.

Emergency services and civilians have clubbed together to rescue people and animals trapped after the quake.

source: AFP