So i work security for a building that has mostly lawfirms and what not . i usually always take a smoke break and talk to the fedex guy when he gets here and leaves. we were outside on the ground level of the parking garage when .I heard a helocopter louder then i ever heard one before . it peaked my curosity so i went to see how close it was. i hear them all the time but because of how loud it was i couldnt ignore it. it was around 400 or 500 feet from the ground probually closer. i saw it coming but didnt see the object it was chasing till about 20 seconds of observing . the object was black and didnt make any noise it was pretty big like almost as big as the helocopter.. it was hard to see ,but it was black and dark grey or brown i couldnt tell because it was night time . it was so odd it was like the shape of a damnn spider i swear to god weirdest shit iv seen. i watched ass the helicopter chased it . ran to get the fedex guy so he could see. by the time he got outside the parking garge both the helicopter and the object were gone . i didnt even hear the copter anymore or see any lights.