Following the explosion, rocks and debris flying through the air were spotted coming down through the roof of the tourist's vessel.

Hawaii's Kilauea volcano erupted in early May, sending a smoldering flow of lava into residential areas on the Big Island. Kilauea was still erupting lava as of Sunday, according to the United States Geological Survey, reported CNN. 

The tour company, Lava Ocean Tours, is presently facing an investigation, Department of Land and Natural Resources, Hawaii, stated.

It said that the concerned company did not have a valid permit to conduct operations.

"Anyone conducting commercial ocean tours of the active ocean entry at Kapoho are required to have a commercial use permit from the DLNR Division of Boating and Ocean Recreation (DOBOR). The owner of the boat involved does have a current and valid permit," it said through a Facebook post.

Among the injured, a 20-year-old woman broke her leg, while a few passengers suffered burns.

"The Hawai‘i County Fire Department reports four people were transported by medics to the Hilo Medical Center by ambulance, nine others went to the hospital in private vehicles and ten people were treated on the scene for minor soft tissue injuries and burns. The most serious injury was a traumatic leg injury suffered by a 20-year old woman. All other passengers who went to the hospital were treated for minor scrapes and burns," it said.

It was not known how many people were present in the boat when the mishap occurred.

Reacting to the news, DLNR Chair Suzanne Case said: “Clearly everyone is interested to learn what happened this morning. In the meantime, all of those injured today are very much in our thoughts for speedy and full recoveries.”

Image: Hawaii DLNR/Facebook