You are responding to a “man with a gun” call. While en route to the call, you s

You are responding to a “man with a gun” call. While en route to the call, you spot a subject matching the description and stop him. He puts something in his waistband, but you cannot tell what it is. You draw your weapon and say, “show me your hands.” He refuses and grabs something from his waist. What would you do and why?