More than 100 federal authorities entered a smoldering fuel depot for the first time Sunday to investigate whether someone intentionally caused an explosion that forced hundreds to evacuate and spewed thick, toxic smoke across the region.
Both the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives sent more than 60 agents each to the Caribbean Petroleum Corp. in Bayamon, a city just west of San Juan, said ATF spokesman Marcial Orlando Felix. Several agents flew in from the U.S.
"Processing the scene is going to be hard," Felix said. "It is big and complicated. ... They are going to take their time."
Luis Fraticelli, head of the FBI's office in Puerto Rico, said he is confident agents will be able to determine "exactly what happened."
He said graffiti found in three different locations in and near San Juan that read "Boom, fire, RIP, Gulf" were still being investigated.
"We haven't discarded anything," he said, while declining to say whether the message was relevant to the investigation. "We're keeping an open mind to all possible investigative leads."
The fire resulting from the explosion affected 21 of the site's 40 tanks, which supply Caribbean Petroleum Corp.'s 200 Gulf gas stations on the island and store jet fuel.
"The fire has been completely put out. The imminent danger in the area has passed," Puerto Rico Governor Luis Fortuno told a news conference. "Now life returns to normal, and we will enter a phase of assistance and reconstruction." He said initial damages are estimated at $6.4 million.
On Saturday, President Barack Obama designated the U.S. Caribbean territory an emergency zone and ordered federal aid to supplement local efforts.
Meanwhile, environmental officials began to clean areas surrounding the site. Both fuel and the foam used to put out fires had seeped into the ground and nearby water sources, said Luis Antonio Ocasio, spokesman for the Environmental Quality Board. Several ducks were found covered in oil.
The fuel-storage tanks exploded shortly after midnight Friday, sending earthquake-force waves that were felt in the capital of San Juan as well as Guaynabo, Bayamon and two other communities.
More than 1,500 people were evacuated, and another 530 sought shelter at a nearby stadium. Several people were treated for minor injuries.
Animal activists said Sunday that they had rescued more than 60 pets from the homes of those affected.
A total of 32 birds, 22 dogs and 10 cats are being kept temporarily at an animal shelter in the city of Carolina, just east of San Juan, said Maritza Rodriguez, president of the adoptionmascotas.com pet-adoption agency.
She says all the animals were found in good condition and that shelter officials will care for them until residents are cleared to return home.
Reuters contributed to this report.
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