Honolulu police are investigating an assault on a boat at Honolulu Harbor Sunday that left a man in serious condition. 

Honolulu police Det. Gary Lahens said one man threatened another man with a knife about 6:45 p.m., then called a group of about five friends who assaulted the victim.

A crew member of the tuna boat vessel Princess Jasmine said the victim is the captain of the vessel. 

An Emergency Medical Services supervisor said the victim, who appears to be in his 50s, was taken to the hospital in serious condition. 

Police arrested the man who allegedly had the knife on suspicion of terroristic threatening and assault. The group of males fled and remained at large.