At least 23 injured as 'lava bomb' hits tour boat near Hawaii's Kilauea volcano

Doyle Rice | USA TODAY

Show Caption Hide Caption Lava bomb crashes into tour boat, injures 23 One person was seriously injured and 22 others hurt after a lava bomb hit a tour boat near the Kilauea volcano on Hawaii's Big Island.

One person was seriously injured and 22 others hurt after a "lava bomb" hit a tour boat near the Kilauea volcano on Hawaii's Big Island, according to emergency officials.

Molten rock running into the ocean exploded and threw chunks of lava onto the Lava Ocean Tours boat, smashing a basketball-size hole through the boat's roof and raining smaller rocks onto the decking. Authorities said most of the injuries were burns or scrapes caused when the hot rocks fall onto the boat and its passengers.

Kilauea makes tiny new lava 'island' The U.S. Geological Survey says the short-lived island in Kapoho Bay was about 20 to 30 feet in diameter.

"Of the injured, four were taken by ambulance, one seriously injured with a fractured femur," Hawaii County officials said in a statement. "Most of the injured passengers had superficial injuries and were treated on arrival at Wailoa Harbor in Hilo."

Big Island resident Ikaika Marzo told Hawaii News Now there was a “huge explosion at the ocean entry." Hot lava can explode when it flows into the cold seawater.

"Eyewitnesses report that it ripped through the tour boat roof and landed on several people – injuring both passengers and crew members," according to Hawaii News Now reporter Mileka Lincoln.

On its website, the company said that "Lava Ocean Tours Big Island lava boat tours are an exciting way to experience the molten hot lava entering the sea. See, Hear & Feel the heat from your front row seat onboard one of our world class catamarans."

A three-hour tour costs $225 and promises a "life-changing experience."

Officials have warned of the danger of getting close to lava entering the ocean, saying the interaction can create clouds of acid and fine glass.

More: A tiny 'island of lava' forms near Hawaii's Kilauea volcano

U.S. Geological Survey volcanologist Wendy Stovall said lava bombs occur when water interacts with lava. The water flashes to steam, which causes the lava to explode into fragments, she said.

Lava from Kilauea has been spewing for more than two months, forcing evacuations. Last month, the U.S. Geological Survey said the lava was transforming into a fast-flowing river capable of covering roughly 200 yards per hour.

In the past few days, a small "island of lava" has also popped up near Kilauea in Hawaii.

Contributing: The Associated Press