Mexico City, Mexico - A magnitude 6.0 earthquake rocked an area near Mexico City on Monday, sending thousands of people into the streets of the capital in fear. The seism, which is being called the strongest aftershock yet from the powerful March 20th quake, happened between the southern Mexican states of Guerrero and Oaxaca.

According to Mexico's Interior Secretary Alejandro Poire, "although the assessments continue, an initial survey of the entire area from air and land had been completed with no catastrophic situation to report. All hospitals, public transport, and essential services are operating normally," he said.

The earthquake struck at 12:36 pm with its epicenter located about 100 miles from Huajuapan de Leon, in the state of Oaxaca, at a depth of about 7.5 miles, according the US Geological Survey.

The USGS initially put the temblor strength at magnitude 6.3 but later downgraded it to a 6.0. More than 40 aftershocks, some measuring up to a magnitude of 5.0, have shaken the Mexican capital and surrounding areas in the aftermath of the March earthquake.

Residents of Mexico City told of panicked people evacuating houses and buildings in many areas of the capital. Thousands of workers poured into the city's main downtown boulevard, Paseo de La Reforma.

Mexico, one of the countries with the highest levels of seismic activity in the world, sits on the North American tectonic plate and is surrounded by three other plates in the Pacific: the Rivera microplate, at the mouth of the Gulf of California; the Pacific plate; and the Cocos plate.

That last tectonic plate stretches from Colima state south and has the potential to cause the most damage since it affects Mexico City, which has a population of 20 million and was constructed over what was once Lake Texcoco.

A magnitude 8.1 earthquake that hit Mexico City on Sept. 19, 1985, was the most devastating to ever hit the country, killing an estimated 10,000 people, injuring more than 40,000 others and leaving 80,000 people without homes.

The most recent powerful earthquake to hit Mexico was a magnitude 7.6 tremor that rocked Colima in January of 2003.