A man and his 3-month-old son are dead Sunday morning, after the man shot the infant and then killed himself.
Investigators say it was a murder-suicide that left first responders in tears -- and it has family members asking why.
Officers responded to a home near Arizona Avenue and Ray Road on Sunday at about 2 a.m. A spokesperson for Chandler Police says officers found 25-year-old Rajneesh Saini dead inside a vehicle with his son on his lap.
The two had been attending a family get-together until Saini brought the boy out to the vehicle and shot the infant and then himself.
Police say Saini's girlfriend is the mother of the baby. They are from Tempe and were visiting her family at the Chandler home.
"For an unknown reason he took his son, walked out to the car and did this horrible deed," said Chandler Police Detective Seth Tyler.
The first 911 call came from someone inside the home almost immediately after the incident.
"The caller was very frantic, said an adult male had just committed suicide and had also killed an infant... just a very traumatic event. When officers arrived on scene, obviously understandably family was outside, they were extremely frantic, very upset."
Detectives are trying to figure out what led to this murder-suicide.
A medical examination will help determine if there may have been any alcohol or drugs in the Saini's system.
Det. Tyler said, however, "We didn't get any indication there was any excessive drinking or anything that would have contributed to him doing this."
A sign on the family's door reads, "No comment, please respect our family's privacy at this difficult time."
The infant's name hasn't been released.