CHP Assistant Chief Ernie Sanchez said Officer Camilleri was struck by a 22-year-old driver who they believe was under the influence of alcohol and marijuana.
Officer Hannah Walcott said the other officer, Trooper Jonathan Velasquez suffered non-life-threatening injuries.
At around 11:30 p.m., a red Cadillac hit the CHP vehicle from behind at high speed, Sanchez said.
Sanchez said the suspected intoxicated driver was coming home from a party and "obviously had too much to drink and too much to smoke" when the collision happened, the East Bay Times reports.
The driver of the auto was also taken to the hospital with major injuries.
CHP officials will hold a press conference at 10 a.m.to provide further details.
Camilleri had been with the CHP for a year and four months.
"We come to you with broken hearts and also anger - not just because we've lost one of our own", Sanchez said.
Gov. Jerry Brown said Camilleri died while "working to keep our communities safe".
CHP says Officer Camilleri is survived by his wife, daughter, sons, parents, brother and sister. "We join his family, friends and the entire California Highway Patrol in mourning his death and honoring his sacrifice".
Flags at the state Capitol will be flown at half-staff in honor of Camilleri, Brown said. He is expected to be charged when he is released from the hospital.
A Hayward CHP officer killed by suspected impaired driver over the weekend.