(CNN) -- A mushroom cloud of thick dark smoke hovered over the Puerto Rican capital after a blast ripped through a fuel storage complex near San Juan early Friday and caused a massive fire.
At least one injury occurred and at least 350 people have been evacuated as about 100 firefighters worked through the night to fight the blaze, Gov. Luis Fortuno said.
Firefighters said it would take a few days to control the inferno. Eleven tanks are ablaze, and firefighters are trying to cool down the remaining 29 tanks. The tanks are holding jet and diesel fuels and gasoline.
Authorities are looking into the cause of the blaze, which took place at Caribbean Petroleum Corp., a storage complex on San Juan's bay that owns the Gulf brand in Puerto Rico.
Justin Gehrke, a U.S. Army civilian employee who filed an iReport for CNN, was taken aback by the sight of the thick black smoke and took photos of the scene from his iPhone.
"I didn't expect to see a mushroom cloud from my house," he said.