Large parts of an oil refinery outside Puerto Rico's capital San Juan have been destroyed by a huge explosion.

The blast was as strong as an earthquake registering 2.8 on the Richter scale. At least two workers were slightly injured. Fourteen storage tanks went up in flames. Smoke billowing over a wide area forced air traffic to be rerouted and schools in the capital to be closed. The authorities expect it will take several days to extinguish the blaze.

Photo: screenshot of Youtube eyewitness video