Oakland police said the assault happened in the 900 block of East 28th Street near Bella Vista Elementary School on Friday afternoon.
Following the assault the victim was able to return to her school and told an adult what had happened to her. The adult reported the assault to police.
Some parents are upset they heard about the sexual assault on the news first. The district says it was tending to the needs of the victim first and now is focusing on campus safety.
"I decided to postpone going to work and come here to find out what's going on, make sure my kid is safe first of all" parent Nefertiti Pollard said.
Parents have a lot of questions following the sexual assault of the girl. An Oakland school district spokesperson told ABC7 News she was alone on the playground after school around 3:30 p.m. Friday when a man came on to campus and lured her across the street to a car and sexually assaulted her.
The suspect is described as a Hispanic male in his early 20s standing between 5 feet 6 inches and 5 feet 10 inches tall, with an average build and black hair.
Officers said the suspect was wearing a blue and black jacket with black shorts at the time of the assault. The suspect's vehicle is described as a silver SUV.
One grandmother says this is unacceptable. "They need to have more staff maybe at the school out here after school is out to make sure the kids are getting picked up.
The district is now scrambling after a three-day weekend to notify parents with a letter. There are also counselors on campus and increased police patrols in the area.
"Everyone here is distraught and we wish we could turn back time and it didn't happen, but the best thing we can do is to make sure our kids are knowledgeable and our parents are knowledgeable with their kids. We're providing information and tips and advice on how to do that," Oakland Unified School District spokesperson Troy Flint said.
This is the third time something like this has happened. On January 24 a girl was touched by a stranger at Think College Now Elementary School and it happened to a 7 year old on March 7 at World Academy.
Police are looking into whether the cases are related.
"Parents are trying to band together to try to think of some safety ways including like a safe route home. Kind of like some car pools, things of that nature so we're hoping that we can band together and kind of get a handle on things," parent Joy Smith said.
Crime Stoppers of Oakland is offering a reward of up to $7,500 for information leading to an arrest in this case.
The district says they plan to issue a letter to parents by Tuesday afternoon.
They're also planning a community meeting for everyone to get together to talk about it and a Stranger Danger meeting to provide more information to families so that they can keep their kids safe. Officials have not announced the date of those two meetings.
The assault remains under investigation and anyone with information is asked to contact the Oakland Police Department's Special Victims Section at (510) 238-3641, the tip line at (510) 637-0298, or Crime Stoppers of Oakland's tip line at (510) 777-8572.
Bay City News contributed to this story.