A moderately strong earthquake shook Mexico's capital Wednesday, but there were no immediate reports of major injuries or damages.

The U.S. Geological Survey said the quake at 7:38 a.m. (8:38 a.m.; 1238 GMT) had a magnitude of 6.2. It was centered near the Pacific coast, about 60 miles (100 kms) east of the resort of Acapulco.

Buildings swayed in the capital and some people evacuated buildings as an earthquake alarm sounded. On the city's main boulevard, one man injured his leg as he rushed out of an office building.

A second, smaller quake followed 24 minutes later. The USGS calculated the magnitude of the aftershock at 5.3.

Mexico City Mayor Miguel Angel Mancera said there no reports of damages from either quake. Civil defense authorities in Acapulco, the largest city near the epicenter, also reported only minor damage, such as broken windows.

Mexico City is vulnerable even to distant earthquakes because much of it sits atop the muddy sediments of drained lake beds that quiver as quake waves hit.

The magnitude-8.1 quake in 1985 that killed at least 6,000 people and destroyed many buildings in Mexico City was centered 250 miles (400 kilometers) away on the Pacific Coast.