Terrifying moment people run for their lives as buildings topple in Mexican earthquake

Pedestrians have been sent running for their lives after the 7.1 magnitude earthquake in Mexico flattened an apartment block onto the streets.

At least 138 people have been killed by the quake that stunned Central Mexico and sent dozens of buildings tumbling into mounds of rubble.

Standing in the middle of an intersection, a group of local residents watched on as buildings swayed from side to side.

What happened next sent them running for their lives - a four storey apartment complex began to drop large pieces of rubble before completely crumbling, creating a huge cloud of dust.

Onlookers were sent running for their lives as the building collapsed in a matter of a seconds. Source: LiveLeak

There were similar scenes across the city with thousands fleeing into the streets in panic.

Mayor Miguel Angel Mancera said buildings fell at 44 locations in the capital alone.

Mancera said at least 30 had died in Mexico City, and officials in Morelos, just to the south, said 54 had died there.

A car crushed by a falling structure. Source: AFP

Rescuers search through piles of rubble for any signs of survivors. Source: AFP

At least 26 others died in Puebla state, according to state disaster prevention chief Carlos Valdes.

Governor Alfredo del Mazo said at least nine had died in the State of Mexico, which also borders the capital.

Mancera said 50 to 60 people were rescued alive by citizens and emergency workers.

The quake caused buildings to sway in Mexico City and sent people throughout the city fleeing from homes and offices, and many people remained in the streets for hours, fearful of returning to the structures.

Alarms blared and traffic stopped around the Angel of Independence monument on the iconic Reforma Avenue.

Electricity and mobile phone service were interrupted in many areas and traffic was snarled as signal lights went dark.

The US Geological Survey said the magnitude 7.1 hit at 1.14pm local time and was centred near the Puebla state town of Raboso, 123km southeast of Mexico City.

At least 21 school children killed in quake

At least 21 school-aged children have died and 100 are reportedly feared missing after the quake destroyed their school.

The four-storey building, which was home to a primary and secondary school, was reduced to rubble in the quake, The Mirror reports.

There have been reports of two children saved and one body found so far.

It's understood around 400 children attended the school, with 100 still unaccounted for.