An earthquake measuring 6.1 on the Richter scale jolted southwestern Mexico\'s Guerrero state at 03:20 a.m. local time (0920 GMT) on Thursday, said Mexico\'s National Seismological Service. The epicenter, with a depth of 40 km, was determined to be at 26 km east of Altamirano city of the Guerrero state, which is at 18.17 degrees north latitude and 100.52 degrees west longitude. The Guerrero state is a geological area which is home to most of the earthquakes that shake the center of Mexico each year. The quake was felt strongly in Mexico City. So far the authorities have not reported about casualties in the city. Patrol helicopters flew over the city to assess possible damage to road infrastructure and buildings. The mayor of Mexico City, Marcelo Ebrard, reported the quake through his Twitter account without providing reports of damage or casualties. While Mexico\'s President-elect Enrique Pena Nieto said in his Twitter account that there was no information of major damage with the 6.1-magnitude earthquake. The quake came just one week after a 7.4-magnitude earthquake hit neighboring Guatemala, leaving 52 people dead and 150 wounded. It was the strongest earthquake that ever happened in Guatemala since Feb. 4, 1976.