May 28 (Bloomberg) -- A magnitude-7.3 earthquake struck under the Caribbean Sea off the coast of Honduras today, killing six people, closing the nation’s largest port and causing a bridge to fall in the north of the Central American country.

Puerto Cortes on the Caribbean coast will be closed at least until tomorrow, though the country’s coffee-growing and other export industries were largely unharmed, Marcos Burgos, the director of the country’s Permanent Emergency Commission, said in a phone interview. In addition to the deaths, 40 people were injured, he said.

A section of a bridge over the Ulua River, Honduras’s biggest waterway, collapsed in the town of El Progreso, Jose Rosario Bonanno Zaldivas, minister of public works, transport and housing, said on HRN radio. The bridge is the country’s link to its second-largest city, San Pedro Sula, and Bonanno Zaldivas said it would take at least 14 months to rebuild.

The quake hit at 2:24 a.m. Honduras time, 63 kilometers (39 miles) northeast of the island of Roatan, at a depth of 10 kilometers, the U.S. Geological Survey said in a statement. The epicenter was 315 kilometers north-northeast of the capital Tegucigalpa. The closest land to the quake was in the palm- fringed Bay Islands, famed for beaches, coral reefs and diving.

Tremors were felt in neighboring countries, including Guatemala. The quake was the largest along an unnamed fault line off the coast of Honduras since a 6.0-magnitude temblor in 2002, the geological survey said. A tsunami watch issued within minutes of the quake for Honduras, Belize and Guatemala was later canceled.

Second Bridge Shut

A second bridge over the Ulua river was shut for inspection, said Bonanno Zaldivas. The four runways at the country’s main international airport weren’t damaged, he said.

Authorities are assessing the damage to the port at Cortes, and it may reopen tomorrow if the facility’s equipment is safe to operate, Burgos said.

Among the fatalities was a 15-year-old boy who died when a staircase in his home collapsed in the town of La Lima, 190 kilometers north of Tegucigalpa, the town’s mayor told CNN.

Several factories and hotels reported damage and one major highway remains shut, Burgos said in the interview.

The heaviest damage was in the Sula Valley, an industrial area with about 1 million residents, Burgos said.

‘Power’s Out’

“There were some serious tremors, but nothing that caused any damage here,” Mel James, reservations manager for the Barefoot Cay resort on Roatan, said today by phone from her home. “The power’s out and a bunch of stuff came off the kitchen shelves.”

Honduras, with a population of about 7.8 million, is the world’s ninth-biggest grower of coffee, according to the U.S. Department of Agriculture.

The tremor occurred along a fault separating the North American and Caribbean plates according to Randy Baldwin, a geophysicist at the geological survey’s National Earthquake Information Center in Golden, Colorado.

“It’s basically where the plates slide past each other,” Baldwin said in a telephone interview. “When an area gets hung up, it takes an earthquake to finally release the built-up stresses.”

The plates slide at the rate of a few centimeters a year, he said.

An aftershock with a magnitude of 4.8 struck the area within an hour of the bigger temblor, the USGS said.

“The significance of the quake being shallow is that it was felt widely throughout the region,” he said.

To contact the reporters for this story: Eric Sabo in Panama City at esabo1@bloomberg.net; Peter S. Green in New York at psgreen@bloomberg.net

Last Updated: May 28, 2009 22:20 EDT