A strong 6.4-magnitude earthquake rattled Mexico City on Thursday, causing buildings to sway, knocking out power and sending people fleeing into the streets. There were no immediate reports of damage or injuries. The US Geological Survey said the quake was centered 15 kilometers (eight miles) north of the town of Tecpan de Galeana in southern Guerrero state. The earthquake had a depth of 23 kilometers. The USGS initially measured it at 6.8-magnitude before revising it down. "At first it felt like a jolt and then it started to move. We are used to it but you never know how long it will last or how strong it will be, which is why we always evacuate," said Daniel Rodriguez, 55, an engineer who fled his second-floor office.