**Officials are investigating the cause of an explosion with the strength of an earthquake which triggered a massive fire at an oil refinery in Puerto Rico.**No-one was killed in the blast early on Friday, which local officials said had the force of a 2.8-magnitude quake.
The explosion happened at the facility owned by the Caribbean Petroleum Corp just outside the capital San Juan.
Some 150 fire-fighters assisted by 250 National Guard troops were involved in trying to contain the blaze.
‘Inferno’
Officials said they did not know what had caused the explosion. The FBI was reported to be helping authorities in their investigations.
“When I went outside, I saw the big orange glow. It looked like daylight over there”
Tamara Rivera, San Juan housewife
In pictures: Puerto Rico blaze
Two people, based at the US Army’s Fort Buchanan base next to the fuel plant, were reported to be hurt when the explosion struck.
The US aviation authority diverted plane traffic from the area due to the billowing black smoke.
One of the first fire-fighters to arrive on the scene described it as an “inferno”, and housewife Tamara Rivera, 37, told Reuters she had initially believed an earthquake had struck.
“But when I went outside, I saw the big orange glow. It looked like daylight over there,” she said.
Puerto Rico is the US self-governing commonwealth in the Caribbean.