The Atlanta school district has moved to end its school security contract with the Atlanta Police Department in the face of warnings from Mayor Kasim Reed that the move could have "catastrophic consequences" for children.

In a letter sent Monday, Atlanta Public Schools operations chief Larry Hoskins notified the city APS would terminate the agreement effective June 30.

APS instead plans to form its own police force and replace the city police officers currently patrolling schools with officers directly accountable to the district.

District officials suggested earlier this year the in-house department could cost more than the district’s annual $5.6 million contract with the city. But district spokeswoman Jill Strickland said this week the new department would not actually cost more. It’s unclear why the cost estimates changed.

Reed said last week that APS’ decision to end its contract with the city police department was “beyond” him.

“Everyone knows APS is independent. They’re expressing their independence. But I think they’re going to make the children of the Atlanta school system far less safe,” Reed said.

“The Atlanta Police Department’s priority is to protect city residents and visitors, which includes students in the Atlanta Public Schools. We will work with APS to ensure a smooth transition so that student safety continues to be our focus, regardless of our physical presence in the schools,” police spokeswoman Elizabeth Espy said in a written statement.

Staff writer Katie Leslie contributed to this article.