Updated

Several fully loaded barges broke loose on the flood-swollen Mississippi River, striking two key bridges and forcing a halt to highway and railroad traffic early Thursday.

Three of the five barges that came loose hit the U.S. Highway 34 bridge that connects Burlington, Iowa, and Gulfport, Ill., said Coast Guard Lt. Cmdr. Tim Whalen.

The landmark bridge, which opened in 1993 and is also known as the Great River Bridge, reopened more than 12 hours after the collision.

One of the three barges also struck the nearby BNSF railroad bridge, which carries dozens of trains a day, including Amtrak, BNSF spokesman Steve Forsberg said. That bridge remained closed Thursday night.

Officials with the Iowa Department of Transportation said inspectors did a visual check of the highway bridge and found only minor blemishes from what apparently was a glancing blow by the barges.

No damage was found to the bridge's deck or support cables, transportation officials said in a news release. An underwater probe was used to check for damage under the water's surface, they said.

While the bridge was closed, motorists had to travel at least 17 miles the nearest highway bridge over the Mississippi River at Fort Madison to Niota, Ill.

Lt. Cmdr. Tim Whalen of the Coast Guard said the barges broke free from a staging area upstream. He did not know who owned the barges. He said the barges were loaded with grain or coal.

Dena Gray-Fisher, a spokeswoman with the Iowa Department of Transportation, said that bridges are designed to absorb an impact, but there was concern about the force of the impact from the barges.

Amtrak spokesman Marc Magliari said passengers on the eastbound California Zephyr, which goes from San Francisco to Chicago, will be transferred to buses for the last leg of their trip Thursday.

The two other barges that broke free from a staging area upstream went aground before reaching the bridges, and they have been recovered, Whalen said.