Published: Mar 20, 2012 8:07 PM EDT

MEXICO CITY (AP) - A strong, long 7.6-magnitude earthquake with an epicenter in Guerrero state shook central southern Mexico and swayed buildings in Mexico City Tuesday. It was followed by a 4.8-magnitude aftershock, according to Mexico's national seismological agency.
    
Plaster fell from ceilings and windows broke in the city center, but President Felipe Calderon said there were no immediate reports of major damage.
    
Frightened workers and residents poured into the streets of the capital just minutes after noon local time (18:02 GMT).
    
Telephone service was down in the city and throughout the area where the quake was felt.
    
"I have problems with pressure, I felt I was going to faint," said Rosa Maria Lopez Velazquez, 62, outside a mall in Mexico City.
    
The quake was felt strongly in southern Oaxaca state next to the epicenter in Guerrero.
    
"It was very strong, but we didn't see anything fall," said Irma Ortiz, who runs a guesthouse in Oaxaca. She said their telephones are down, and that the quake shook them side-to-side.
    
The U.S. Geological Survey set the intensity of the first quake at 7.6 and said the epicenter was 11 miles underground. Mexico's National Seismological Survey said the trembler had an epicenter southwest of Ometepec in Guerrero state.
    
Mexico City Mayor Marcelo Ebrard's Twitter account said the water system and other "strategic services" were not experiencing problems.
    
Groups of women hugged and cried at Mexico City's Angel of Independence monument, where hundreds of people evacuated from office buildings said they never had felt such a strong earthquake. Others typed ferociously on their Blackberries.
    
Samantha Rodriguez, a 37-year old environmental consultant, was evacuated from the 11th floor on the Angel Tower office building.
    
"I thought it was going to pass rapidly but the walls began to thunder and we decided to get out," she said.
    
Mexico City's airport was closed for a short time but there was no damage to runways and operations were returning to normal.

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