We still do not know the complete circumstances that led to the shooting of two young women in Napa on Saturday, but now one man and two similarly young women have been arrested.

According to Napa police, a 22-year-old Vallejo man, John Nicholson Jr., was arrested Monday evening at 7:23 pm, in connection with Saturday's shooting on the 400 block of Riverside Drive in Napa.

The shooting occurred just after 8 pm Saturday near the Napa Abajo neighborhood — which is just across the Napa River and a few blocks south of the Napa Valley Expo, where BottleRock takes place, and about eight blocks from Oxbow Public Market.

Two young women, one of them a juvenile, were fatally shot, and one was declared dead at the scene. The other later died at the hospital.

It was reported on Monday that the victims appeared to police to be very young, perhaps around 15 years old, but the Napa Valley Register reports their ages as 17 and 19. They have not yet been publicly identified.

The Napa Police Department earlier said, "The victims are acquaintances and have familial ties to Napa." KRON4 reported that a makeshift memorial at the scene of the shooting included a fabric heart that said "RIP Sasha" on it.

Subsequent to Nicholson's arrest, around 3 am Tuesday, Sonoma Sheriff’s Office Detectives arrested two other involved suspects, who have been identified as 19-year-old Jessica Whitten and 19-year-old Judith Adolph, both of Santa Rosa. Both women have been booked on suspicion of aiding in a felony.

Nicholson is suspected to have been the shooter, and he has been booked on two counts of murder.

One witness, Brandon Perez, told KTVU that that a group of young women had been seen arguing near some boats in the area, by the side of a building, just before the shooting the occurred.

Homicides are rare in Napa, let alone double shootings that occur before nightfall.

Joshua Boules, who lives in the neighorhood where the shooting occurred, told KTVU that while things could be "rough" in the neighborhood sometimes, but "nothing like what happened last night."

Napa police are still seeking more witnesses and digital evidence. Anyone who has information should contact Detective Dustin Dodd at 707-257-9568 or [email protected].

Photo: Google Street View