Details are very light; however, an armed man wearing body armor was arrested shortly before President Trump arrived at the American Airlines arena in Dallas Texas.
According to NBC5 Dallas:
Dallas police arrested the man while he was wearing a helmet, a vest and a backpack. Officers confiscated a gun, a breathing mask and an aerosol can. The man, who has not been identified, was arrested near counter-protestors. (link)
According to additional reporting the gunman was located with of a group of protesters against the U.S. withdrawal from Syria.
NOW: More video of man arrested outside Trump rally. Walked near counter protestors wearing vest, helmet, backpack. Police confiscated a gun, breathing mask, knee pads & some type of aerosol can. Secret Servide are here. @NBCDFW https://t.co/XPQsQJRNHL pic.twitter.com/0Z0u59ZMpm— Meredith Yeomans (@YeomansNBC5) October 17, 2019