LOS ANGELES, July 16 (Xinhua) -- A lava bomb from the Kilauea Volcano in the Big Island of Hawaii struck an ocean tour boat on Monday, injuring 23 people, the Hawaii County Civil Defense Agency said.

Most of the injured passengers suffered superficial injuries and one is seriously injured with a fractured femur, according to the Hawaii County Civil Defense Agency, adding that a "basketball-sized lava bomb" punctured the vessel's roof, and debris from the explosion littered its floor.

The Lava Ocean Tours Inc. vessel was within the 300-meter safety zone instituted by the U.S. Coast Guard at the time of the explosion, officials were quoted as saying by a local news outlet, the Honolulu Star-Advertiser.

The safety zone was set up around the ocean entry of lava on the island's southeast side to protect people and vessels from potential hazards of the active flow.

There were 52 people, including 49 passengers and three crew members on board when the tour boat was hit by the lava bomb and debris. One of the railings of the boat was also damaged, another local news outlet, the Hawaii News Now, reported.

According to the official website of the Lava Ocean Tours Inc., lava boat tours are an exciting way to experience the molten hot lava entering the sea.

"See, hear and feel the heat from your front row seat onboard one of our world class catamarans," the company lures visitors with exciting words. "Lava is flowing now! Come experience the historic Kapoho Bay Ocean Lava entry today!"

Hundreds of homes have been destroyed by lava from the Kilauea Volcano which has been erupting nearly continuously since early May. The volcano is one of the youngest and most active volcanoes in the world.