Puerto Rico woke up in darkness on Tuesday morning after a power grid failure left nearly all of the island without electricity. Around 90% of clients were without power at 9:30 a.m. (1330 GMT), according to energy distribution company Luma Energy's real-time portal. It will likely take 24 to 48 hours to turn the lights back on, "conditions permitting," Luma said in a statement. "While the cause of the outage is under investigation, preliminary findings point to a failure in an underground line," Luma added. Ivan Baez, a spokesperson for power generator Genera, called the grid failure a "major incident"...