CHARLOTTESVILLE, Va. (WVIR) - Investigators are trying to get to the bottom of an online threat that closed all public schools in Charlottesville.

The threat came in on Wednesday, March 20, on a platform that allows people to comment anonymously.

But officers are working with state and federal agencies trying to figure out who’s behind it.

Charlottesville police say they were notified about the threat around 3 p.m. Wednesday, and the school system made the call to cancel classes on Thursday late Wednesday evening. As a result, over 4,500 students are out of school for the day.

"Our first priority is safety of our students and our staff," Rosa Atkins, the schools' superintendent, said.

Screenshots posted from a site known as 4chan show that the person wants to do an "ethnic cleaning" targeting black and Hispanic students.

"Hate and racism is something that we don't tolerate in our school system, nor do we tolerate it in our community," Atkins said. "And I think we all have to keep in mind a threat against one student - no matter what the ethnicity - is a threat against all of our students."

Charlottesville police officers say they’re still trying to find the identity of the person and if anyone knows who the person is, they should call the police.

“It's not enough to just consider that how the students may feel, this is an entire community that's been rocked by violence and hate,” Charlottesville Police Chief RaShall Brackney said. “So that the students, the staff, and the community at large, this is a really disheartening turn of events for us here after the past two years.”

As a result of the online threat against Charlottesville High School, Albemarle County has increased security at schools across the county on Thursday.

The Charlottesville Police Department will not go into detail on what safety precautions will be taken when schools open, but officers want to make sure it's a safe and welcoming environment.

"Know that we're considering every possibility, knowing that Charlottesville is always at the center of national attention we have to make sure that we prepare for anyone who may want to continue to keep us there," Brackney said.

The school system says it understands it takes time for the police department to investigate and it will give them time to continue the process.

Charlottesville City Schools will remain closed on Friday, March 22.

The following message was sent to city schools families and staff on Thursday evening: 

"Dear families--

Thank you for understanding our decision to close today. We heard clearly that you, too, want us to prioritize the safety of our students and staff.

The police and other state and federal authorities have told us that this remains an active investigation. We will keep you posted of developments as we learn more. Based on extensive conversations with law enforcement, we have decided to remain closed on Friday, 3/22. Police have asked anyone with information to contact 434-970-3280.

We would like to acknowledge and condemn the fact that this threat was racially charged. We do not tolerate hate or racism. The entire staff and School Board stand in solidarity with our students of color -- and with people who have been singled out for reasons such as religion or ethnicity or sexual identity in other vile threats made across the country or around the world. We are in this together, and a threat against one is a threat against all.

We know that many of you have questions about how to talk to your students about why schools are closed. We suggest a brief acknowledgment of the situation. (For instance, for young students, you might say, “Someone said they wanted to hurt some students, and the people who run the schools decided that it would be safer for students to stay home.”) Then follow your child’s lead as they ask questions or show emotions.  We have links to additional resources, below.

Have a good evening. We will give you any further updates as we learn them, but in the meanwhile, we appreciate your patience as we continue to place safety first."