A strong earthquake hit Mexico early today, knocking out power in parts of Mexico City and sending frightened residents into the streets of Acapulco. Civil defense officials in Mexico and the Pacific coast state of Guerrero, where the quake was centered, said there were no reports of any deaths, serious injuries or major damage. According to the Associated Press, the quake had a preliminary magnitude of 6 and was centered 40 miles (64 kilometers) northwest of Acapulco, the U.S. Geological Survey said. It hit at 12:42 a.m. (0542 GMT) local time, setting off alarms and sending people out into the streets in their pajamas. Gerard Fryer of the Pacific Tsunami Warning Center said the quake was too small and too far inland to produce a tsunami. Mexico City Civil Defense Secretary Miguel Moreno Brizuela said the quake knocked out power to about 20 percent of the homes in the city's downtown district. -- SPA