A strong earthquake struck Puerto Rico early Tuesday morning, the latest in a series of quakes to hit the U.S. territory in recent days.The 6.4-magnitude quake was located near the southern coastal city of Ponce, according to the U.S. Geological Survey, revising its initial reading of 6.6-magnitude.A number of powerful aftershocks followed the quake, including one measure 6.0.The Pacific Tsunami Warning Center issued an alert immediately after the quake was reported, but it was later canceled.The Puerto Rico Electric Power Authority says power was been shut off across the the entire island after automatic protection systems at all of its power plants were activated.  The authority said one of the country’s primary power plants near the quake’s epicenter had been damaged but that power was expected to be restored to the island later Tuesday.At least one person was killed in Tuesday’s quake. A Ponce city official said a 77-year-old was killed in his home after a wall fell on him.The quakes have caused heavy damage in some areas. The Ponce official said many buildings were damaged. In the southern coastal town of Guayanilla, the church in the public plaza collapsed, the mayor said in an interview on a local radio station.Governor Wanda Vazquez says all non-essential government employees have been given the day off, as more aftershocks are anticipated throughout the day.The island has been shaken by numerous quakes of varying degrees since the night of December 28.  A 5.8-magnitude quake on Monday leveled several homes in the southern coastal town of Guanica and destroyed a coastal rock formation known as Punta Ventana in nearby Guayanilla.  The formation, shaped like a round stone window, was a popular tourist attraction. 
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