Two people have been confirmed dead after a huge explosion at an Exxon Mobil oil and gas facility on Staten Island, one of the five boroughs of New York City.
The barge sank soon after the explosion
Officials in the city, which has been on high alert since the 11 September attack in 2001, have stressed that there is no indication of terrorism.
The Federal Bureau of Investigation says it is still too early to determine the precise cause of the explosion which occurred as a barge was offloading fuel at about 1010 local time (1510 GMT).
A spokeswoman for Exxon Mobil said the bodies of two barge workers had been found in the water and another worker was being treated in the hospital with serious burns.
About 30 other workers at the site of the blast were unhurt.
New York Mayor Michael Bloomberg said: "There is absolutely no evidence and no reason to think that this is anything other than a very tragic industrial accident.
"All of the damage was confined to the barge and the very immediate vicinity, within yards."
The manager at the terminal, Hank Muller, said: "We are greatly saddened by the injuries and loss of life."
The barge refuelling at the terminal on the Arthur Kill waterway was carrying 100,000 barrels of fuel.
Some 200 firefighters rushed to the scene of the blast in what a fire department spokesman described as a "major emergency response".
Plumes of black smoke rising up in the sky between New York City and New Jersey could be seen for many miles.
Donald Laub, from Tottenville Public Library on the island, heard the blast.
"At first we thought it was some sort of terrorist incident. 9/11 is not that far away. Everyone is a little bit jittery right now," he told the BBC.
Coastguard officials said the port authority had closed down the waterway to all but the emergency services.
New York Fire Department spokesman Michael Loughran said the fire had quickly burned itself out without spreading to any of the major
storage tanks at the plant.
Only a few residents closest to the facility were evacuated from the area.
The barge sank soon after the explosion.
Mr Bloomberg said officials were unsure how much of the gasoline had burned and how
much was still in the vessel.
Exxon Mobil said a contract firm, Clean Harbors, had been mobilised to conduct an environmental clean-up once the fire had been completely extinguished.
The BBC's Stephen Evans says the Staten Island facility pipes supplies to large areas of the US from the north-east to mid-western states, and the three New York-area airports.
Oil prices rose by almost a dollar per barrel on world markets after news of the blast.