A Kings County welfare fraud investigator killed a Lemoore police officer and critically wounded his father before killing himself in a shooting during a birthday party, California authorities said.

Kings County sheriff’s detectives said 32-year-old Ramiro Trevino Jr., died after fatally shooting 31-year-old Johnathan Diaz and critically wounding his father 58-year-old Ramiro Trevino Sr.

Diaz was a friend of Trevino Jr. and was present to celebrate Trevino Sr.’s birthday and Diaz was off-duty when he was killed, authorities said.

The shooting occurred around 9 p.m. Saturday, Nov. 2, at a birthday party for Trevino Sr.,  just outside of Hanford, the Hanford Sentinel reported.

Witnesses told detectives that Trevino Sr. and Diaz, along with other people at the party, intervened in a fight between TrevinoJr. and his girlfriend and got her to safety.

But when Trevino Sr. and Diaz tried to cool him off, Trevino Jr., armed with multiple firearms started shooting.

Deputies then believe Trevino Jr. committed suicide by shooting himself.

Trevino Sr. was transported to Kaweah Delta Medical Center in Visalia, where he remains in critical condition, KGPE reported.

This story is developing.