Twenty-three people on a Lava Ocean Tours vessel were injured Monday morning after what’s being described as a “lava bomb” hurled molten lava onto and through the metal roof of the boat.

It happened at around 6:05 a.m.

A passenger who was on board the Hot Spot told KHON2 she and her boyfriend watched in horror as fiery rocks flew toward them.

“It was just surreal. I didn’t even believe that this was coming towards us,” said Erin Walsh. “We’d been watching it, and it was so beautiful. Then all of a sudden, it was like, oh my God. I need to get away from this. There’s nowhere to go.”

Walsh says it took two hours from the time the lava bomb hit to get back to shore. We’re told a surgeon on board helped care for those who were hurt.

The boat returned to Wailoa Boat Harbor in Hilo, where it was met by emergency medical personnel, first responders, and state and county officers. The state tells us there were 52 people on board, including the captain and two crew members.

A Hilo Medical Center spokeswoman said doctors treated a total of 13 people. Nine drove themselves while four came by ambulance.

While most were treated for minimal burns and abrasions, one person was flown to Oahu in serious condition, said Elena Cabatu, Hilo Medical Center. The patient was a 20-year-old woman who suffered “an injury to the pelvis.”

The Hawaii Fire Department says 10 more were treated at the scene for minor soft tissue injuries and burns.

“Everybody was calm and listened to directions that were given so we could extricate the one patient who was seriously injured,” said Battalion Chief Matthias Kusch, Hawaii Fire Department. “Then there was an orderly move through the triage system so everybody was very cooperative.”

“Hilo Medical Center was at the ready when we got the call. We were able to keep our night shift crew on to help the day shift with the influx of 13 patients,” said Cabatu.

“In total, we had about 45 staff in our ED to assist with this trauma activation that included staff from administrative leaders, emergency department, imaging, lab, trauma program manager, and a team of emergency physicians, trauma surgeons, orthopedic surgeon, and an anesthesiologist. Incident command was set up in our emergency department to coordinate patient care,” she added.

The incident is now under investigation by DLNR’s Division of Conservation and Resources Enforcement, the U.S. Coast Guard, and the Hawaii Police Department.

The roof of the aluminum vessel has a hole about the size of a basketball. Lava also damaged the railings and parts of the cover for the propellers.

Investigators with the state and the Coast Guard inspected the vessel throughout the day and took the GPS, which will determine where exactly the boat was when it happened.

“I want to stress that at this time, this investigation is in the very early stages and therefore we’ll have no comment to make as far as what the investigation is looking like, or any of the findings thus far,” said Jason Redulla, DOCARE assistant enforcement chief.

Anyone conducting commercial ocean tours of the active ocean entry at Kapoho is required to have a commercial-use permit from DLNR’s Division of Boating and Ocean Recreation (DOBOR). 

Right now, four companies have this permit: Lava Ocean Tours, Moku Nui Lava Tours, Kalapana Cultural Tours, and Hawaiian Lava Boat Tours.

The U.S. Coast Guard established a permanent safety zone which extends 300 meters (roughly 328 yards) around all ocean-entry points. It’s unclear if the boat was in this zone at the time of the explosion, Redulla said.

The company also has permission to use Wailoa harbor as its base of operation, after voluntarily relocating from the Pohoiki boat ramp, which is about a half-mile from the current active ocean entry.

A volcanic bomb is a mass of molten rock that forms when a volcano ejects viscous fragments of lava during an explosive eruption that cool into solid fragments before they reach the ground.

“I would use an example of something that I used to do as a child. We would heat a marbles, and glass marbles, and we would drop them in cold water, and we would watch them crackle and watch them break apart,” explained Janet Babb, a U.S. Geological Survey geologist. “Same thing. Hot lava entering cooler sea water cools quickly, and there is going to be this steam that blasts it apart.”

In May, a Kapoho resident was hit by a lava bomb while he was outside his home, nearly shearing his leg in half.