A Dutch Harbor seafood processing plant was severely damaged by an explosion Monday evening a public safety official said was likely caused by the ignition of fine fish-meal dust, though the incident remained under investigation Wednesday.

Mike Holman, director of Unalaska's Department of Public Safety, said the blast — first reported by public radio station KUCB — occurred inside the Westward Seafoods plant on Captains Bay Road at about 6:45 p.m. Monday. Thirteen members of the department responded.

There were employees inside the building at the time of the explosion, but no injuries were reported. Westward Seafoods President Mark Johanson confirmed employees were in the facility, which he described as mostly "one large open space," but were thankfully uninjured.

The blast likely occurred when an undetermined ignition source detonated dust from the production of fish meal, often used as feed for other fish, Holman said.

Johanson said the exact cause of the blast was still undetermined, though fish-meal dust was among the possible culprits. He declined to mention other possible causes.

"I don't want to speculate at this point," Johanson said. "We'll do our investigation and obviously we'll learn from it."

Johanson said the fish-meal plant was closed for the time being, due to the extent of the damage.

"There's quite a bit of damage inside the building — some of the pipes erupted, and one of the doors was blown off its hinges into a container," Holman said.

Holman said no foul play is currently suspected in the blast, which is also being investigated by the state fire marshal. The plant's sprinkler system extinguished the resulting fire before crews arrived but contributed to damage estimates well beyond the $100,000 first reported after the fire.

"It sounds like the sprinklers, when they went off, they dumped a lot of water on all the electrical equipment," Holman said.

Johanson said one pollock season was wrapping up and the fish-meal plant isn't needed in any current fishery openings. The company was optimistic the plant will be fully operational in time for another pollock season in January, he said.

Holman said he has seen two fish-meal dust explosions at Dutch Harbor plants during his 21 years with the department, but those blasts hadn't been as costly as the one Monday.

"I don't think it has caused as much damage as this one," Holman said. "This was a little bit bigger."

News Editor Ben Anderson contributed to this report.