Steve looked up as one of the S.H.I.E.L.D. radios went off, expecting another attack, but not one from an armed enemy. The radio buzzed with talk of gun fire, and Steve tugged on his cowl, scooping up his shield as he jogged for the exit. He pulled out his id card, and gave a hasty, "Avengers, Assemble."
Who in their right might would attack them in a time like this? There were civilians inside! He took the stairs two and three at a time to try and get down to the square, waiting for a response.