Police have identified the victims as 29-year-old Cassandra Flores, 9-year-old Hillary Armendariz, 5-year-old Damaris Armendariz and 2-year-old Matias Armendariz.
The deceased suspect has been identified as 28-year-old Ruben Armendariz.
According to OKCPD, officers responded to a home in the 7400 block of NW 5th Terrace around 11:30 p.m. on Wednesday. Upon arrival, police found five people with gunshot wounds, three of whom were deceased.
Officials say the suspect and one of the children were still alive when officers got there. Both were taken to nearby hospitals where they later died.
Investigators say they believe Ms. Flores and Mr. Armendariz were married but separated. It appears Mr. Armendariz shot the four victims before shooting himself.
OKCPD says it is still early in the investigation and detectives are working to discover what led to the incident.
Anyone with information is asked to call the Homicide Tip-Line at 405/297-1200.