A 5.6 magnitude earthquake hit southern Mexico today, shaking buildings far away in the capital, Mexico City, but there were no immediate reports of deaths or damage.
Hundreds of people evacuated buildings in the capital, many of them wearing surgical face masks due to the deadly swine flu outbreak that is suspected of causing 149 deaths in Mexico.
The quake's epicentre was about 240 km from Mexico City in the southern state of Guerrero, home to the Pacific coast resort of Acapulco.
"It felt really strong here. There's been no one hurt or killed ... we're monitoring the situation in the area," said Marcos Gonzalez, a civil protection official in the city of Chilpancingo near the epicentre.
The USGS revised the quake's magnitude down to 5.6 from 6.0 initially, adding that the quake was 25.6 miles (40 km) deep. Quakes of magnitude 5.6 are classified as moderate, capable of causing considerable damage.
However, there were no immediate reports of deaths or damage from the quake in Mexico City, whose sprawling metropolitan area has a population of about 20 million, a civil protection official said.
The Mexican peso, already battered by jitters over the swine flu outbreak, fell back to its earlier lows immediately after the earthquake.
Mexico's health minister, Jose Angel Cordova, said on Monday that the outbreak of swine flu was suspected to have killed 149 people in the country and the number of cases was seen rising.