A strong earthquake has struck Mexico City, sending thousands of residents into the streets, according to reports.

The United States Geological Survey said the earthquake was marked as a 7.1 magnitude that hit the southern Mexico region Tuesday. In response to the quake, Mexico City International Airport has suspended operations.

The quake hit five miles from the Mexican state of Puebla at a depth of 32 miles, the USGS added.

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Rescue crews and ordinary citizens searched through rubble for survivors as night fell on Tuesday on battered cities in central Mexico, including the capital, where the death toll from a major earthquake grew to at least 149.

The magnitude 7.1 quake toppled dozens of buildings, broke gas mains and sparked fires less than two weeks after another powerful quake killed at least 98 people in southern Mexico. It also hit just hours after emergency drills marked the anniversary of a temblor that killed thousands in 1985.

Millions of people fled into the streets, where they weathered the violent shaking and desperately sought word about the welfare of family and friends.

Emergency personnel in Mexico City, a metropolitan region of about 20 million people, searched frantically with picks and shovels for survivors beneath the rubble of what the sprawling city’s mayor calculated to be as many as 44 collapsed buildings, including at least one primary school.

Mexican President Enrique Peña Nieto said late on Tuesday more than 20 children and two adults had been found dead at the school, Colegio Enrique Rebsamen, in the neighbourhood of Coapa. Another 30 children and 12 adults were missing, he said.

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At least 226 people were killed by a powerful earthquake that struck central Mexico on Tuesday, the nation's civil protection agency said.