Aurora Police Chief Kristen Ziman said the gunman, identified as Gary Martin, 45, was an employee at the industrial complex.
Two of the people injured in the shooting were taken to Rush Copley Medical Center in Aurora where they are being treated for non-life-threatening injuries, hospital spokeswoman Courtney Satlak said in an email to Reuters.
The wounded police officers were in stable condition at a local hospital, Clayton Muhammad, spokesman for the City of Aurora, told the local ABC affiliate.
Video on local media showed numerous police cars surrounding a large commercial building in Aurora, the ground covered in snow.
Witness John Probst told CNN in an interview that he saw the gunman, a co-worker, running down an aisle of the manufacturing facility with a pistol equipped with a laser sight. Probst told the network that he saw people bleeding.