About five people remain unaccounted for after a deadly explosion at an under-construction power plant, and a section of the site was too unstable to search, a fire official said on Monday.

Sunday morning’s blast at the Kleen Energy Systems plant in Middletown, about 30 km south of Hartford, killed at least five people and injured a dozen or more others. It happened as workers were clearing gas lines of air.

Middletown Deputy Fire Marshal Al Santostefano said officials had verified the whereabouts of 95 per cent of the nearly 100 workers who were at the plant, citing conversations with contractors and labour union officials. It was unclear whether the workers who remain unaccounted for are missing or have not been contacted yet by authorities.

Investigators returned to the scene Monday to try to begin determining the cause.

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