Officials have warned residents to stay away from the fuel storage fire blazing in Puerto Rico.
(CNN) -- The massive clouds of black smoke reminded Carlos Salgado of the horrifying television images he'd seen of the terrorist attacks of September 11, 2001.
That's how powerful the explosion was at a fuel storage complex in Puerto Rico on Friday. It shook the ground with the force of a 2.8-magnitude earthquake, shattering windows and doors and sending panic through the streets.
Early Saturday morning, 24 hours after the blaze erupted, Salgado stood on the balcony of his San Juan home, about 10 miles from the blast site, and could still see fireballs illuminate the night sky from his home.
"I've never seen anything like this in Puerto Rico," said Salgado, the legal counsel for the emergency corps that manages ambulances on the Caribbean island.
He could still hear explosions, and acrid air burned his nostrils as winds shifted westward, carrying the toxic smoke over populated areas of the island.
Firefighters were working around the clock, battling to contain the raging blaze. A cause for the blast has not been determined. Officials said they plan to investigate.
The scope of environmental damage is also not known.
Officials are concerned that expected precipitation Saturday mixed with the smoke could lead to acid rain. Authorities urged residents not to venture outside and to bring in their animals during the rain.
At least 15 of the 40 tanks at the Caribbean Petroleum Corp. facility in the municipality of Catano were still burning, Gov. Luis Fortuno said at a Friday evening news conference. The governor had put the tally at 11 a few hours earlier, indicating that the fire was still spreading.
The blaze erupted shortly after midnight Friday, when at least one fuel tank exploded. Residents described a surreal scene after the blast woke them.
That's how powerful the explosion was at a fuel storage complex in Puerto Rico on Friday. It shook the ground with the force of a 2.8-magnitude earthquake, shattering windows and doors and sending panic through the streets.
Early Saturday morning, 24 hours after the blaze erupted, Salgado stood on the balcony of his San Juan home, about 10 miles from the blast site, and could still see fireballs illuminate the night sky from his home.
"I've never seen anything like this in Puerto Rico," said Salgado, the legal counsel for the emergency corps that manages ambulances on the Caribbean island.
He could still hear explosions, and acrid air burned his nostrils as winds shifted westward, carrying the toxic smoke over populated areas of the island.
Firefighters were working around the clock, battling to contain the raging blaze. A cause for the blast has not been determined. Officials said they plan to investigate.
The scope of environmental damage is also not known.
Officials are concerned that expected precipitation Saturday mixed with the smoke could lead to acid rain. Authorities urged residents not to venture outside and to bring in their animals during the rain.
At least 15 of the 40 tanks at the Caribbean Petroleum Corp. facility in the municipality of Catano were still burning, Gov. Luis Fortuno said at a Friday evening news conference. The governor had put the tally at 11 a few hours earlier, indicating that the fire was still spreading.
The blaze erupted shortly after midnight Friday, when at least one fuel tank exploded. Residents described a surreal scene after the blast woke them.
"I was in bed and all of a sudden heard this really horrible sound, so I ran upstairs and thought the whole town had blown up," said Teo Freytes, who filed an iReport for CNN.
Others also woke Friday morning to an extremely unusual sight.
"I didn't expect to see a mushroom cloud from my house," said Justin Gehrke, a U.S. Army civilian employee who also filed an iReport.
Fortuno said he declared a state of emergency for the area so Puerto Rico can get aid from the Federal Emergency Management Agency.
The storage and refinery complex sits near San Juan's bay, and Fortuno said officials are working to protect the water from being affected.
"We have serious worries that the bay or other bodies of water could be contaminated," he said.
Caribbean Petroleum's Web site says the complex has storage facilities for gasoline and gasoline-related products.
"We have been monitoring the water visually, and we have installed preventive pads and other material to contain a spill," said Pedro Nieves, chairman of the Puerto Rico Environmental Quality Board. "No oil has reached the water."
But Nieves said that Caribbean Petroleum has a history of spills and that "there was potential that it had contaminated ground water."
iReport.com: See, share, send images of the explosion
Newspaper and TV reports said a 4-inch pipe from a lagoon on the complex was broken, preventing firefighters from using 2 million gallons of water from the lake to battle the blaze. About 150 area firefighters and 215 National Guard personnel were battling to keep the blaze from spreading.
One person suffered smoke inhalation and was taken to a hospital, Fortuno said. At least 350 people were evacuated to a nearby stadium.
The smoke can be toxic for people with breathing conditions, and officials have asked nearby residents to stay away, the governor said.
"This is a tremendous amount of smoke, and fire contains all kinds of irritants, and this is oil that is burning," said Mary Mears, spokeswoman for the Environmental Protection Agency region that includes Puerto Rico. "It's smoke, so you're going to notice coughing, tearing, maybe a sore throat."
The Bureau of Alcohol, Tobacco and Firearms sent a team of fire investigators but has to determine whether the fire was an accident or set deliberately, said Orlando Felix, ATF resident agent in charge of the office in Puerto Rico. Federal agencies have jurisdiction over Puerto Rico, which is a commonwealth of the United States.
The FBI confirmed it is investigating graffiti found on two San Juan tunnels that referred to a fire. A spray-painted message on the two tunnels, less than 3 miles apart, said: "Boom, fire, RIP, Gulf, Soul, ACNF."
Rodriguez and San Juan police spokeswoman Maria Del Pilar Bon said they did not know what or who ACNF is. But Caribbean Petroleum owns the Gulf Oil brand in Puerto Rico.
"There could be many reasons [for the fire]," Fortuno said. "We're not going to guess. But there has to be an investigation."
Caribbean Petroleum spokeswoman Frances Rios said five employees were at the facility at the time of the explosion but declined to provide more information, El Nuevo Dia newspaper reported on its Web site.
Caribbean Petroleum, which owns 200 gas stations in Puerto Rico and several inland distribution facilities, supplies much of the island's fuel. But the governor said Puerto Rico has enough gas to last 24 days and 20 days' worth of diesel.
Department of Consumer Affairs Secretary Luis Rivera Marin said 16 million gallons of gasoline were in transit to the island. He also froze prices at the level they were at 8:06 a.m.
Officials transferred 295 inmates from a high-security prison in the area to other facilities, which they declined to identify for security purposes. Another 1,600 prisoners were moved from another nearby facility. About 200 extra prison officials were brought in to handle the transfers, Fortuno said.
Schools in Bayamon, San Juan, Toa Baja and Catano were closed, as were several roads.
CNN's Susan Candiotti, Jackie Castillo, Khadijah Rentas and Moni Basu contributed to this report.
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