LOS ANGELES >> The twin ports that handle 40 percent of America’s import trade were mostly back in business again after an idle day brought on by smoke from a fire at an old wooden wharf.

The last of the 14 container terminals at the ports of Los Angeles and Long Beach is expected to be reopened on Wednesday morning.

All eight container terminals at the Port of Los Angeles and three of the six at the Port of Long Beach were closed most of Tuesday because of worries about unhealthy smoke, but all but one were running again for the night shift nearly 24 hours after the fire was sparked by a welding accident, port officials said.

That ignited the 800-foot-long, pre-World War II wharf with creosote-preserved timber that brought concerns over the plume of dark smoke it produced.

The wharf is part of a terminal that processes cargo that isn’t confined to large, stackable containers.

Fireboats spraying water and foam worked with scuba divers and firefighters ashore to contain the bulk of the fire after about 2 1/2 hours, but it continued to smolder Tuesday night, and officials did not know when the final embers would be out.

"This is a very, very difficult fire to fight," said Los Angeles Fire Department Chief Ralph Terrazas.

The economic impact of the fire was not immediately known and will depend on what kind of cargo was held on the docks. Port of Los Angeles spokesman Phillip Sanfield said he expected the dollar loss would be minimal because dockworkers have been able to catch up following similar-length disruptions due to weather or labor unrest.

He estimated a few thousand employees, mostly longshore workers, were sent home Tuesday.

The Port of Los Angeles handles an average of about $780 million of cargo each day, and the consequences of delays in moving that much product will reverberate down the supply chain — from truckers who wouldn’t get paid for the day to exporters and retailers whose products won’t show up right on time.

Outside the port, the fire’s main impact came in the form of precautions for potential health effects from smoke.

Fire and police officials advised residents in the Wilmington and San Pedro neighborhoods as well as the city of Long Beach to remain indoors and keep windows closed.

One parochial school was closed Tuesday, and students at a public elementary school were bused to another site, said Monica Carazo of the Los Angeles Unified School District. Other schools remained open with outdoor activities suspended.

Terrazas said, however, that hazardous air quality levels were reported only in the immediate proximity of the fire.

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Associated Press writers Justin Pritchard and Andrew Dalton in Los Angeles contributed to this report.