A gunman decked out in body armor was arrested this afternoon near the helicopter pad at Boston Medical Center, police said.The unidentified suspect was arrested around 4:25 p.m. after a Boston University special officer spotted him near the hospital’s helipad on Albany Street, Boston police spokeswoman Officer Rachel McGuire said.It is unclear what the man is being charged with, McGuire said, and police officials are currently investigating the incident.Boston Medical Center referred all comment to police.Developing...