An earthquake measuring 6.3 struck southwestern Mexico Monday, sending thousands of people into the streets of the capital in fear. There were no immediate reports of casualties or damage. The quake struck at 1736 GMT with its epicenter some 158 kilometers (98 miles) from Huajuapan de Leon, Oaxaca, at a depth of 12.3 kilometers (7.6 miles), the US Geological Survey said. Residents said the quake rocked the capital, Mexico City, causing panicked residents to flee houses and buildings in many areas of the city. Thousands of people poured into the city\'s main downtown boulevard, Avenida La Reforma, from buildings alongside it. But Mayor Marcelo Ebrard said on his Twitter account that there were no immediate reports of damage. \"We have an earthquake again. Evacuation underway,\" he said. \"We have no damage yet.\" Mexico City\'s police chief, Manuel Mondragon, said an initial survey of the city from the air and land had been completed \"with no catastrophic situation to report.\" On March 20, a quake measuring 7.4 on the moment magnitude scale struck Guerrero and the neighboring state of Oaxaca. Two people died and another 13 people were hurt. The earthquake -- with its epicenter south of the Pacific resort of Acapulco -- was the most powerful to hit the country since a deadly temblor in 1985, which destroyed entire neighborhoods of the capital, Mexico City. More than 40 aftershocks, some measuring up to 5.0 magnitude, shook the Mexican capital and southern areas in the aftermath of the March earthquake, according to the National Seismological Service.