MEXICO CITY (AP) -- A magnitude 7.1 earthquake rocked central Mexico on Tuesday, killing more than 200 people as buildings collapsed in plumes of dust and thousands fled into the streets in panic.
Dozens of buildings collapsed or were damaged in in densely populated parts of Mexico City and nearby states. A column of smoke rose from a structure in one central neighborhood in the capital, one of the world’s biggest cities with more than 8 million inhabitants.
Market stall vendor Edith Lopez, 25, said she was in a taxi a few blocks away when the quake struck. She said she saw glass bursting out of the windows of some buildings. She was anxiously trying to locate her children, whom she had left in the care of her disabled mother.
At one school in the south of the capital 20 children died and search and rescue teams worked into the night to save missing pupils buried in the rubble.
Survivors said an alarm sounded shortly before the quake hit giving people little time ot evacuate buildings. In the city center one of the main streets, Reforma Avenue, filled with office workers as buildings emptied fast.
Local media broadcast video of whitecap waves churning the city's normally placid canals of Xochimilco as boats bobbed up and down.
President Enrique Peña Nieto said 27 buildings had collapsed or partially collapsed in Mexico City.
Mexico City's international airport suspended operations and was largely without power. Many passengers were trapped in the terminal as nearby roads were blocked.
Peña Nieto was flying to the southern state of Oaxaca to survey relief operations there after the Sept 7 quake, when Tuesday's quake struck. His plane diverted back to Mexico City where it had to land at a military base.
Much of Mexico City is built on former lake bed, and the soil acts like gelatin, amplifying the effects of earthquakes centered hundreds of miles away.
Earlier in the day workplaces across the city held readiness drills on the anniversary of the 1985 quake, a magnitude 8.0 shake, which killed thousands of people and devastated large parts of Mexico City.
Morelos Gov. Graco Ramirez reported on Twitter that at least 42 people had died in his state south of Mexico City.
At least 26 others died in Puebla state, according to Francisco Sanchez, spokesman for the state's Interior Department.
Gov. Alfredo del Mazo told the Televisa news network that two people died in the State of Mexico, which also borders the capital: a quarry worker who was killed when the quake unleashed a rockslide and another person who was hit by a falling lamppost.
There were no immediate official reports of deaths in the capital, but journalists witnessed some people who had apparently died.
Rescue workers rushed to the site of damaged or collapsed buildings in the capital, and reporters saw onlookers cheer as a woman was pulled from the rubble.
Rescuers immediately called for silence so that they could listen for others who might be trapped.
Gala Dluzhynska said she was taking a class with 11 other women on the second floor of a building on the 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.
"There were no stairs anymore. There were rocks," she said.
They reached the bottom only to find it barred. A security guard finally came and unlocked it.
The U.S. Geological Survey said the magnitude 7.1 hit at 1:14 p.m. (2:15 p.m. EDT) and it was centered near the Puebla state town of Raboso, about 76 miles (123 kilometers) southeast of Mexico City.
Puebla Gov. Tony Gali tweeted that there had been damaged buildings in the city of Cholula including collapsed church steeples.
The new quake appears to be unrelated to the magnitude 8.1 temblor that hit Sept. 7 off Mexico's southern coast and which also was felt strongly in the capital.
U.S. Geological Survey seismologist Paul Earle noted that the epicenters of the two quakes are 400 miles (650 kilometers) apart and most aftershocks are within 100 kilometers.
There have been 19 earthquakes of magnitude 6.5 or larger within 250 kilometers of Tuesday's quake in the past century, Earle said.
Earth usually has about 15 to 20 earthquakes this size or larger each year, Earle said.
Initial calculations show that more than 30 million people would have felt moderate shaking from Tuesday's quake. The US Geological Survey predicts "significant casualty and damage are likely and the disaster is potentially widespread."