BATON ROUGE, Louisiana -- Several grain barges broke loose from a towboat and three of them sank, prompting the Coast Guard to close a five-mile stretch of the flood-swollen river near Baton Rouge on Friday.

Coast Guard Senior Chief Michael Berry did not know if high water contributed to the accident. Three barges sank and one was corralled at the bank. Berry said the river was closed for the investigation, but he did not know when it might reopen.

Coast Guard Petty Officer Bill Colclough said no injuries or pollution were reported after the barges broke loose around 2 p.m. local time.

Louisiana's transportation department said the barges sank near a bridge, which was closed for about half an hour for inspection.

On Thursday, authorities reported the first person to die in Mississippi floodwaters since the mighty river began climbing out its banks last month in the Midwest -- a 69-year-old man who apparently collapsed in the high water.

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At least eight deaths in Arkansas have been attributed to flooding, but all of those happened in flash floods or Mississippi tributaries.

On Friday, Coast Guard Commandant Adm. Robert Papp toured parts of the flooded river and was briefed about efforts to control shipping traffic. He began in Natchez, Mississippi, where Coast Guard personnel said the river is expected to fully recede by mid-June. Officials said they plan to eventually spend at least a week re-marking the river so cargo ships and barges can safely navigate the waterway.

Experienced river pilots say they have never seen anything like the roiling current now racing to the Gulf of Mexico. Since spring floods pushed the Mississippi to historic heights, America's businest inland waterway has become one of its most challenging to navigate.

"If you're not scared of it, you should be, because it has a lot of ways of hurting you," Travis Morace said this week as he slowly nudged his tugboat, the Bettye M. Jenkins, along the river bank near Vidalia, Louisiana. Morace has been running boats on the Mississippi for two decades.

The high water brings with it a host of hazards. Debris is everywhere, and the unusually swift current makes it difficult for pilots to go upstream. Good luck stopping if you're headed downstream. For those who make their living on the water, the river is a respected adversary in the best of times. Now it just plain frightens them.

On Friday, the Mississippi at Vidalia looked more like a stormy ocean than a river. Whitecaps frothed under the bridge that connects the city to Natchez, Mississippi, and whirlpools churned across the channel.

In many places, obstacles were hiding just beneath the surface. Some trees in Natchez were nearly submerged. A basketball hoop protruded about 2 feet above the water at a flooded-out court.

The current was filled with flotsam of every sort, including whole trees and long, green ribbons of vegetation. A nearby alligator struggled against the water's pull, finally finding refuge on the porch of a building partly concealed by the rising water.

Earlier in the week, the Coast Guard briefly closed a 15-mile span of the river near Natchez because of the current and concerns that the wakes from passing vessels would put pressure on floodwalls protecting communities. The wakes were also washing floodwater into some businesses.

Although the river was soon reopened, barge and tug traffic is still being tightly regulated.

The Coast Guard normally asks vessels to maintain a minimum speed of 3 mph going upstream. But these days, they can go only about 1 mph to avoid generating wakes. When heading south, many have trouble stopping in the fast current.

"You ask me, they should close it down altogether," said Jerry Batson, captain of the tug Gladys Batson. "It's awful risky for any vessel."

Farther south in Louisiana, the high water also presents a challenge to pilots who guide oceangoing vessels into ports from New Orleans to Baton Rouge.

Michael Lorino, head of the Associated Branch Pilots, said pilots have to maneuver through tricky currents made worse by the river's many bends, and they must stay away from sandbars built by the huge amount of silt carried down during high-water season, usually in the spring.

They have to learn, and re-learn, the river every day, all while dodging towboats, cruise liners, ferries and massive grain and chemical ships.

Many ships entering the river are bound for the Port of South Louisiana, which lines both sides of the Mississippi north of New Orleans. It's the nation's largest port in terms of tonnage, and it handles more than half of America/s grain exports.

The port handles about 60,000 barges a year, along with 4,500 to 5,000 deep-draft vessels.

That kind of commercial traffic means closing the river is costly. Huge ships waiting to take on cargo can run up expenses of $40,000 a day, and port officials say the total cost of a day's closing can top $300 million.

When the water began to climb, the shipping industry was one of the biggest proponents of opening spillways to divert excess water from the Mississippi. The Army Corps of Engineers first opened the Bonnet Carre spillway north of New Orleans, then the Morganza spillway north of Baton Rouge.

Those actions helped keep ports open and eased pressure on the levees protecting Baton Rouge and New Orleans.

Ports downstream are still open until the surge of water arrives. But in Vidalia, about 140 miles upriver from New Orleans, a lot of business has come to a halt. The river crested in that area Friday at nearly 14 feet above flood stage, a level that was lower than first predicted but about three feet higher than the 1937 record.

Forecasters said it could be days before the water begins to recede.