Firefighters tackled a giant blaze fuelled by 5,600 tons of rubber at the Port of Savannah in Georgia, where a towering column of black smoke could be seen from miles away.
By early this morning, the fire department said its crews had contained the fire, but it could take a while for the flames to burn out inside a warehouse covering 226,000 square feet at the port's Ocean Terminal just west of central Savannah.
"It is contained," Savannah Fire and Emergency Services spokesman Mark Keller said, after the fire had burned for at least five hours.
"Will it burn all night? There's no telling. It's solid blocks of rubber that are burning."
He said firefighters were surrounding the warehouse with hoses on three sides and using industrial pumps to suck water from the Savannah River and blast in through water cannons.
The cause of the fire was not immediately known, but all port workers were accounted for and unharmed.
No mandatory evacuations have been ordered, but the authorities are asking people in the historic district, Savannah's tourism hub, to stay indoors as much as possible to limit exposure to smoke.
"Please limit the time you're out," Mr Keller said, adding he did not expect people to cancel dinner reservations or shopping trips.
"If you're finished at the restaurant or finished with shopping, go back to your hotel room or go home."
Keller said firefighters probably will not be able to get close enough to investigate the cause until later today.
"Solid rubber blocks, they're going to burn and we're going to keep putting water on it," he said. "We'll just do it until the fire's out."
Savannah-Chatham County police closed some streets near the port terminal and smoke slowed traffic on the Talmadge Bridge that spans the Savannah River to South Carolina.
Police also asked a few hotels near the port terminal and the Savannah College of Art and Design, which has buildings in the area, to either evacuate or keep people inside.
"We're not worried about the fire getting over there at this point," said police spokesman Julian Miller. "It's the smoke. It's going to be heavy, oily and ugly."
Robert Morris, spokesman for the Georgia Ports Authority, said the burning area contained about 5,600 tons of imported raw rubber used in manufacturing.
"The warehouse is full of rubber, so it's a rubber fire," he said.
The Port of Savannah is the fourth-busiest seaport for containerised cargo in the US. The Ocean Terminal, which covers 200 acres, handles farm equipment and other heavy machinery as well as cars and bulk goods such as wood products and steel.