Police said a 45-year-old man at a Waikiki gun range pointed the barrel of a gun at himself on Sunday night.
A 31-year-old male staff member intervened, attempting to pull the gun from the man.
The gun went off during the ensuing scuffle, but no one was injured, police said.
The incident occurred 6:50 p.m.
The 45-year-old man fled before officers arrived. Police opened a reckless endangering case, but no arrest has been made while police investigate.