MEXICO CITY (Reuters) - A powerful earthquake late on Thursday in Mexico killed at least 26 people, authorities said, raising the number of fatalities after the governor of the southern state of Oaxaca said on Friday that 20 people were killed in that region. Oaxaca governor Alejandro Murat said 17 of the 20 fatalities were in Juchitan, a town on Mexico s Tehuantepec isthmus. 