Hyde County sheriff's officials said the victims worked for Melrose Pyrotechnics of South Carolina, adding they were preparing the island's July Fourth fireworks when the explosion happened about 9:15 a.m., WITN-TV, Washington, N.C., reported.

Authorities said ferry service to the coastal island was suspended in the wake of the blast.

"The explosion happened near the ferry docks," Ocracoke Island resident Gwen Myers told the broadcaster. "It was unreal. There was a huge boom. The explosion peeled the top off the 18-wheeler truck."

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