The incident happened around midnight in the 600 block of West La Deney Avenue near San Antonio Avenue.
According to Ontario police, a couple got into a fight near a home in the area. The boyfriend, identified as 18-year-old Matthew Rodriguez, got into the passenger seat of a black Honda driven by a friend, identified as 19-year-old Isaac Cesares.
Investigators say Cesares then intentionally struck Rodriguez's 19-year-old girlfriend, her 21-year-old sister and their mother, who were all walking away from the location.
Authorities say all three women suffered non life-threatening injuries and were transported to an area hospital for treatment. Their wounds were described as scrapes and bruises, and they're expected to be OK.
Cesares, of Ontario, initially sped off but was later arrested for driving under the influence with injuries, hit-and-run and assault with a deadly weapon. He was booked at West Valley Detention Center. His car was impounded pending further investigation.
Rodriguez, of Hacienda Heights, was also arrested for making terrorist/death threats, but he was later released.
If you have any information about this incident, you're urged to contact the Ontario Police Department at (909) 395-2001.