(AP) — Police say at least six people are injured after a shooter opened fire at a FedEx center north of Atlanta.

Cobb County police spokesman Michael Bowman says an active shooter was reported early Tuesday at the FedEx package sorting facility in Kennesaw. He says police have surrounded the building and are working to clear it. He calls the situation “active and fluid.”

Marietta police spokesman David Baldwin says six injured patients were taken to nearby Wellstar Kennestone Hospital, one of them with potentially critical injuries. Police didn’t’ immediately say if anyone has died.

FedEx spokesman Scott Fiedler says the company is cooperating with authorities.