The crash occurred just before 6 p.m. near Oxnard Street and Vineland Avenue.
All four people were taken to a hospital for treatment of their injuries. A 5-year-old boy was listed in critical condition. The woman and the two other children suffered moderate injuries and were also taken to a hospital, according to the Los Angeles Fire Department.
There's no word as to whether the injured were in a crosswalk.
The condition of the driver was unknown. The crash was being investigated by Los Angeles police.
City News Service, Inc. contributed to this report.