Tuesday's earthquake hit hardest in border area of southern Oaxaca and Guerrero states, one of the strongest earthquakes to shake Mexico since the deadly 1985 temblor that killed thousands in Mexico City.  Officials confirmed that some 800 homes were damaged, with another 60 having collapsed.  This quake was the strongest shaking felt in the capital since a magnitude-6.5 earthquake struck in Guerrero in December.

Hours after the shaking at noon local time (18:02 GMT), there were still no reports of death or serious injury, even after a less powerful, magnitude-5.1 aftershock was felt in the capital and several other aftershocks near the epicenter in a mountainous rural region.

"It was very strong, very substantial," said Campos Benitez, hospital director in Ometepec, about 15 miles (25 kilometers) from the epicenter.  Guerrero Gov. Angel Aguirre, who is from Ometepec, was headed there to survey the damage and ordered emergency crews and civil protection to the area to help with the damage.  The state did not say how many were displaced.

In Mexico City, frightened workers and residents poured into the streets of the capital.  Telephone service was down in the city and throughout the area where the quake was felt and some neighborhoods were without power.  The airport closed for a time but officials said there was no runway damage and they resumed operations.

Mexico City, built on a lakebed, was badly damaged in 1985 when an 8.1 earthquake killed at least 10,000 people.  In past years, Guerrero has suffered several severe earthquakes, including a 7.9 in 1957, which killed an estimated 68 people, and a 7.4 in 1995, which left three dead.

The U.S. Geological Survey set the preliminary magnitude of the first quake at 7.4 and said the epicenter was 11 miles underground.  The survey set the aftershock at 5.1.  Seismologists and civil protection officials said there didn't appear to be heavy damage or casualties because of where and how the earthquake hit.

There have been 15 earthquakes of magnitude 7 or stronger since 1973 within 310 miles (500 kilometers) of Tuesday's quake.  Weaker buildings collapse with each quake, leaving a cadre of stronger ones that can withstand the shaking.

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 BlackBerrys.

Mexico City's airport was closed for a short time but there was no damage to runways and operations were returning to normal.