When she called her boss he told her to wait outside while he checked.
But seeing nothing unusual inside he told the 25-year-old not to worry and went back to his office.
Maria said: "No sooner had my boss gone than I heard the noise again.
"I pulled my service revolver out and went in and then I saw this black shadow flying across the room towards me.
"Before I could react it grabbed me and I screamed and ran full pelt to the bathroom where I locked myself in.
"I then noticed there was blood on my face, arms and chest and realised it had scratched me."
Other police officers have reported seeing a woman and girl covered in blood at the academy.
Read Full Story: Daily Star UK