Hartford police officers were dispatched to Aetna headquarters at about 10 a.m. to handle a report of a suspicious male.
Upon arriving on the scene officers met with building security who had detained Denrey Wadlington.
Further investigation showed that the man was detained by security within three minutes of entering the building while carrying a backpack that contained an AR-style pistol.
The suspect was then taken into custody by Hartford police and transported to the Hartford Police Headquarters.
Wadlington is facing charges of criminal trespassing, possession of a firearm, illegal possession of an assault weapon and possession of a large capacity magazine.
The investigation is being handled by the Hartford Police Major Crimes, Crime Scene and Intelligence Divisions.