(CNN) -- The killings of four people, including two U.S. Navy pilots, in a Coronado, California, apartment early New Year's Day was a murder-suicide, investigators said Wednesday.
Lt. J.G. John R. Reeves, 25, put a gun to his own head and killed himself after shooting to Lt. J.G. David A. Reis, 25; Karen Reis, 24; and Matthew Saturley, 31, according to the San Diego County Sheriff's Department.
The murder-suicide conclusion was based on the medical examiner's autopsy, the sheriff's statement said.
Homicide detectives will not provide a suspected motive for Reeves' actions until more interviews are conducted and evidence is collected, the sheriff's statement said.
"It is anticipated this process, and the crime laboratory report, could take several weeks," the statement said.
The two Navy officers, roommates in the apartment where the shootings happened, were F/A-18 jet pilots assigned to Marine Fighter Attack Training Squadron 101, Marine Aircraft Group 11, Third Marine Aircraft Wing, the Navy said.
Reeves earned his Navy commission through the ROTC program at Penn State University in 2008, while Reis was commissioned in the Navy after completing the ROTC program at the University of New Mexico the same year, the Navy said.
The Coronado Police Department got a call around 2:20 a.m. Sunday about shots being fired inside a condominium in the coastal city, which is just southwest of San Diego. Responding officers found a man's body in the doorway and the other bodies inside the residence, according to a press release from Lt. Larry Nesbit of the San Diego County Sheriff's Department.