According to the Hawaii County Fire Department, the incident occurred early Monday morning. A lava bomb punctured the roof of the boat, leaving a large hole in the vessel and damaging one of the boat's railings.
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The boat managed to return to Wailoa Harbor in Hilo around 7 a.m. with the twelve passengers - all with varying degrees of injuries.
Of the 12 injured passengers, three were taken by ambulance to Hilo Medical Center. Two passengers were in stable condition. One, a woman in her 20s, was in serious condition with a fractured femur. The remaining nine passengers drove themselves to the hospital, and the fire department reported that their injuries were superficial.
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Kilauea volcano beams through the clouds in mesmerizing time lapse
Kua 'o Ka La Public Charter School was destroyed by lava last week, along with nearby Ahalanui Beach Park.
ABC News contributed to this report.