A strong earthquake rattled southern Mexico on Wednesday, killing a man, damaging buildings in five coastal towns and causing panic in the capital.

The quake, which struck at 2:22 am (0722 GMT), lasted around half a minute and was powerful enough to shake buildings more than 300 kilometers (200 miles) away in Mexico City.

A roof beam fell on a 49-year-old man and killed him in his bed in the town of San Andres Huaxpaltepec, near the epicenter in southern Oaxaca state, local civil protection official Carlos Ramos told AFP.

An undetermined number of buildings were damaged in at least five towns, Ramos said.

Both Mexico's Seismological Institute and the US Geological Survey said the quake measured 6.5 on the moment magnitude scale, though the USGS later revised down the quake's strength to magnitude 6.2.

The epicenter was located 125 km (80 miles) west-southwest of Oaxaca city, near the Pacific coast, according to the USGS, which monitors quakes worldwide.

The quake had a depth of 20 km (12.4 miles), the USGS said.

Some scenes of panic were reported in Mexico City, where memories of the magnitude 8.1 quake of September 19, 1985 that killed between 10,000 and 30,000 people, are still raw.