Five men were injured, two of them critically, in a fire on a docked a long-line fishing vessel at Honolulu Harbor Friday afternoon.

The initial 911 call came in at about 3:30 p.m. for a “person on fire,” Honolulu Emergency Services Department Director Dr. Jim Ireland said.

The state Department of Law Enforcement said an explosion occurred while the men were working in the engine room of the Kim Thu, a foreign long-line fishing vessel docked at Pier 36.

First responders arrived at the scene of “what appears to be an explosion on a fishing boat,” according to an Emergency Medical Services report.

EMS initially sent two crews and a paramedic district chief, who arrived at the scene to find multiple patients needing treatment. EMS sent an additional three crews to respond to the five adult men with multiple burn injuries, Ireland said.

Ireland said that an explosion appeared to have happened aboard the boat, but that all of the patients EMS treated were on the pier when the crews arrived.

Three of the victims were in critical condition and were taken to the Queen’s Medical Center, but they will be transferred to Straub Medical Center’s Burn Unit, state officials said. Two victims were in stable condition and were taken to Straub

The cause of the fire is under investigation