NEW: All people are believed to be accounted for, a fire spokesman says
2 barges with natural gas explode on the Mobile River, the fire department says
3 people were injured and transported to a local hospital, Mobile firefighters add
The blast occur near where the Carnival Triumph is docked, a Coast Guard official says
(CNN) -- A fire broke out Wednesday night on Alabama's Mobile River after two barges loaded with natural gas exploded not far from where a once listless Carnival cruise ship was docked, authorities said.
The Mobile Fire-Rescue Department, on its official Twitter feed, reported that it had "units on the scene on east side of Mobile River where a fuel barge has exploded and is on fire." Minutes later, the fire department issued an update stating that two barges had exploded.
Three people who were burned were transported to a local hospital, fire department spokesman Steve Huffman told CNN. He did not describe the severity of their injuries. All people are believed to have been accounted for, Huffman added.
There were at least three explosions tied to the incident, Mobile Fire-Rescue noted around 9:30 p.m. (10:30 p.m. ET) on Twitter.
Huffman said Wednesday night that authorities hadn't determined what caused the blasts.
A 1-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.
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 Greg Botelho and Chandler Friedman contributed to this report.