A power blackout hit swaths of Venezuela on Monday, including in the capital of Caracas and a major oil-producing province, darkening office buildings and homes and knocking out city traffic lights, witnesses said, according to Reuters. It was the second time this year the OPEC nation's electricity grid, creaking from outdated infrastructure, has suffered a major outage. Venezuela's oil refineries are hit by frequent outages. But it was not immediately possible to reach officials from the state-run oil industry for information on Monday's blackout. In some parts of the country, like the major provincial town of Barquisimeto, electricity was lost for only a few seconds. In Caracas and the oil state, power remained off more than 20 minutes after the blackout.