Victor Siharath, 36, is accused of causing the violent collision that also left two other people injured, including a 12-year-old girl, Los Angeles County District Attorney George Gascón announced at a news conference.
The two-vehicle crash, which was captured on surveillance video, happened Saturday around 11 p.m. at White Avenue and Phillips Boulevard as a group of five people were returning home from the baby shower.
The deceased victims were identified by family members as Yesenia (Ochoa) Olaez, 33; Lorena Morales, and Alejandra Olaez, 33. The celebration the group had attended was for Morales' granddaughter.
"My sister-in-law, she didn't need to die that way," Morales' brother-in-law Paulino Alvarez told reporters outside the courthouse after Tuesday's hearing.
Siharath, a Pomona resident, was driving an SUV and was arrested at the crash site. Witnesses reported seeing him run a red light right before the collision. Gascón said Siharath was traveling "well above the speed limit of 35 miles per hour."
Juan Manuel "Jaime" Garcia, was the front-seat passenger and the husband of Lorena Morales. He was transported to a hospital in critical condition.
In the backseat was Noemi Olaez, the daughter of Alejandra. The 12-year-old girl was also hospitalized in the intensive-care unit.
Nephew of victim in alleged DUI crash in Pomona speaks out: 'I wanted her to see me grow up'
"There are no words to express the heartbreak that Mr. Siharath's actions have caused these victims' families and community," Gascón said. "Our hearts go out to the grieving families and the survivors as they attempt to cope with this unimaginable tragedy."
Siharath was formally charged with three counts of murder and one count of driving under the influence of an alcoholic beverage causing injury. He has a prior DUI conviction in San Bernardino County, the district attorney said, adding that he was given a legal warning at the time that if he drove drunk again and caused a death that he could be charged with murder.
If convicted as charged, Siharath could face a maximum sentence of life in prison, prosecutors said. He was being held without bail Tuesday and is due back in court on March 28.
Relatives said Yesenia Olaez was in the process of adopting her 11-year-old nephew when she was killed. The boy, Brian Gonzalez, said at a vigil Sunday that she was "a loving mother."
"I feel like her time was way too short," he said tearfully. "Although I do know she died that peacefully and she died loving me. I wanted her to see me grow up."
GoFundMe pages have been established to help the families of the three women who were killed:
Yesenia Olaez.
Lorena Morales.
Alejandra Olaez.
A car wash fundraiser is scheduled for Sunday to help pay for the victim's funeral costs. The event will be held from 11 a.m. to 5 p.m. at Hector's Smog Check, 1081 West Holt Avenue in Pomona.