Police responded to an apartment complex on the 1400 block of South Park Avenue in Pomona around 5:51.
Responding officers found two suspects suffering from non-life threatening stab wounds.
During the later investigation, it was revealed that both suspect were family members that allegedly become involved in an argument that escalated into a fight.
That's when the men, identified as Gilbert Alcantera, 23, and Erik Soto, 33, both of Pomona produced knives and stabbed each other in the upper body.
The investigation is ongoing but both men are facing assault charges.
Anyone with information regarding the incident was urged to contact the Pomona Police Department at (626) 909-620-2085.