The crash happened just before 4 p.m. in the area of Hayes and Roosevelt streets near Liberty Elementary School.
Riverside police said the woman and the two children were in a marked crosswalk when they were hit by a vehicle described as a blue-colored 2020 Range Rover.
The woman and one of the children died at the scene. The second child was transported to a hospital with minor injuries.
According to a preliminary investigation, a 46-year-old Riverside resident was driving the Range Rover westbound on Hayes Street and approaching Roosevelt. The three pedestrians began crossing Roosevelt Street in the marked crosswalk as the SUV entered the intersection.
Police said the driver made a southbound turn onto Roosevelt and struck the woman and two children as they crossed the roadway.
It does not appear drugs or alcohol were a factor in the crash and the driver cooperated with the investigation, police said in a news release. The driver was not injured in the crash.
The names and ages of the victims were not immediately available.
Anyone with information regarding the crash is asked to call Riverside police at (951) 826-8720.