The familiar yellow and white bags of Domino sugar are once again rolling off the conveyor belts at the Key Highway plant, one week after an explosion blew out windows and rendered the powdered sugar mill a total loss.

There is more work to be done, with windows still being boarded up yesterday. But managers picked up mops and workers volunteered overtime to get production lines operating again in advance of the busy holiday baking season.

"It was a spectacular effort," refinery manager Stuart FitzGibbon said at a news conference yesterday at the Museum of Industry on Key Highway.

The trademark Domino sign gleamed orange-red atop the nine-story sugar plant and a white plume of smoke rose from its stacks, signaling it was back in business. But a number of windows on multiple floors remained gaping holes.

Investigators are still looking into what caused the explosion on the ninth floor and a fire on the sixth floor that appears to be unrelated.

They are paying close attention to the system that manufactures confectioners' sugar, which takes up floors 7, 8 and 9. Dust explosions are a risk in sugar manufacturing and authorities immediately suspected the dust collection system. The dust raised when sugar is moved from one place to another can be volatile if the right conditions exist.

Damage estimates are in the "tens of millions," FitzGibbon said.

About 175 of the plant's 400 workers were at the 85-year-old plant at the time but no one was seriously injured. Much of the process is automated, and only a few workers are needed to monitor the lines, FitzGibbon said, which prevented more casualties.

"I feared there was dead people," FitzGibbon said, recounting his first thoughts after the blast.

When Charles Benton heard the boom, his mind raced back 10 years to Nebraska, when a similar blast at a sugar plant killed one of his co-workers and injured numerous others and leveled a third of the building.