Authorities kept their distance as a fire raged on board a pair of fuel barges on Thursday morning, hours after exploding at a docking area on Alabama's Mobile River.
Steve Huffman with Mobile Fire and Rescue said conditions remain too volatile for fire crews to approach. At least six explosions have been reported and were heard up to 20 miles away.
Just half a mile across the river, Alan Waugh, the general manager at the Ft. Conde Inn, said he saw and heard the initial explosion when it happened.
"We were up on a second floor balcony and the sky lit up in orange and yellow," he told CNN affiliate WALA TV. "It sounded like planes above you dropping bombs when it first went off."
Huffman said Wednesday night that authorities hadn't determined what caused the blasts, but were in the process of being prepped for reload when the explosion happened. The fire department's Twitter feed said they were filed with gasoline.
A one-mile safety zone has been set up around the barges, U.S. Coast Guard Cmdr. Eric King said. Authorities have closed the shipping channel and were letting the fires burn.
Three people who were burned were transported to a local hospital, according to Huffman. CNN affiliates reported that the victims were taken to USA Medical Center and are in critical condition.
All people from the scene are believed to have been accounted for, Huffman said.
The fires burned near the docking area of the Carnival Triumph, he added. The Triumph has been based at the BAE Shipyard in the Port of Mobile since an engine fire in February left it crippled and adrift in the Gulf of Mexico with more than 4,200 people aboard.
For four days, tugboats guided the disabled ship into the port as passengers complained about miserable conditions onboard.
CNN's Tina Burnside, Dave Alsup, Jessica Jordan, Greg Botelho and Chandler Friedman contributed to this report.