Gerald Herbert / AP

A fire still burns on Wednesday after a tugboat and barge hit a gas pipeline Tuesday evening in Perot Bay in Lafourche Parish, La., about 30 miles south of New Orleans.

NEW ORLEANS -- A gas pipeline burned Wednesday morning in a bayou south of New Orleans hours after it was hit by a tug boat pushing an oil barge, but authorities say no oil appeared to be leaking from the barge.

Coast Guard Cmdr. Russ Bowen said it appears the barge is intact and none of its cargo of crude oil was leaking, though there were patches of oily sheen in the area. The Coast Guard was investigating whether those sheens were related to the accident.

A plume of smoke rising from the site could be seen from downtown New Orleans Wednesday morning. Bowen said authorities planned to allow the gas to burn itself out before approaching for a closer inspection. The area is thinly populated and no evacuations had been ordered.

Four people aboard the 47-foot tug Shanon E. Settoon were injured, one severely, in the collision Tuesday at about 6 p.m. CDT. Water at the collision site is very shallow.

The 19-mile section of pipeline was carrying liquefied petroleum gas. It had been isolated from other conduits by its owner, San Ramon, Calif.-based Chevron, so only what was inside could burn.

"All crew members were able to exit the tug; the captain reportedly suffered second to third-degree degree burns," the Coast Guard said in a news release early Wednesday.

The barge was holding 92,000 gallons of crude oil, the Coast Guard said. The tug boat had 1,000 gallons of diesel fuel. Settoon Towing of Pierre Part, La., lists the tug among its vessels on its website.

Bowen said it was believed that the diesel fuel aboard the tug had burned up.

WWL-TV reported that the tug's captain was transferred to the burn center at Baton Rouge General Hospital.

It was not immediately known who owns the 154-foot oil barge.

The area is along the northern reaches of Barataria Bay, which was heavily affected by oil from the BP spill in 2010. It is mostly small communities where people often make their living from the sea, either working in the oil and gas industry or as fishermen.

The 92,000 gallons the Coast Guard says was being carried by the barge is a fraction of the millions of gallons that spewed into the Gulf of Mexico during the 2010 spill.

The region where the fire was burning is crisscrossed by pipelines and wellheads are a common sight in the shallow waters of the bayou and bay shoreline.

Bowen said it's not unusual for tugs to operate in shallow areas. "That's just the nature of coastal Louisiana," he said.

Beyond that, he said he couldn't comment on why the accident happened.

Bayou Perot was the scene of an explosion and fire on a specialized oil rig in December 2010 in which three men were injured. The explosion happened while the men were welding and there was no pollution, the Coast Guard reported.

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This story was originally published on Wed Mar 13, 2013 5:19 AM EDT