The team track the vigilante to the building across from city hall, within hearing range, where Oliver is addressing the press. The vigilante fires on the team with an automatic weapon, multiple times, yet no one at the press conference reacts to the sound of gunfire.
When Vigilante was waiting in the building across from City Hall, a security guard is checking the floor undergoing renovations. Vigilante hits him with a tranq dart, the guard falls down unconscious but doesn't place his head on the floor like he would if he was out cold.