A powerful earthquake shook south and central Mexico on Friday, causing people to flee buildings and office towers in the country's capital. Crowds of people streamed out on to the streets of Mexico City as the ground shook. The U.S. Geological Survey put the quake's preliminary magnitude at 7.2 and said its epicenter was 33 miles northeast of Pinotepa in Oaxaca state. It had a depth of 15 miles. The epicenter is a rural area of western Oaxaca state near the Pacific coast and the border with Guerrero state. Pictures of masonry in the streets appeared on social media but Oaxaca's civil protection service said no serious damage had been reported so far.