The incident took place on Benson Avenue near G Street, right on the border of Ontario and Montclair. It started shortly before 11 p.m. Thursday when police received reports of shots fired from the 1500 block of West H Street.
Investigators say there was a dispute between two neighbors on H Street, where the suspect opened fire on his neighbor. The man then holed up in his house and refused police instructions to surrender. The suspect's neighbor was not injured.
SWAT officials evacuated nearby houses and surrounded the suspect's home. After several hours, officers entered the house and found the suspect dead from an apparent self-inflicted gunshot wound.
The identity of the suspect was not immediately released. He was only described as a 40-year-old Ontario resident.
The motive for the initial shooting and the reason the suspect took his own life has not yet been determined.
If you have any information about this incident, you're urged to contact the Ontario Police Department at (909) 986-6711.