The gunshot to the metal door scared people into silence mere moments after Gamora had tackled the guard to the ground. In fact, she was still on all fours on top of the man who probably had sustained a head injury, seeing as he was out like a light once he had hit the ground. The shot made her scramble to turn to the door, but she remained low.
"This is it. They're here." She said into the communicator, then turned to the fighters. "If they shoot you, doesn't matter what powers you have, they'll kill you. They almost killed two Asgardians already. Stay off their range but take them down!"
Her words were drowned out by open fire. As soon as one of the men saw the first person who didn't look, strictly speaking, average human, he opened fire. There was panic, people scrambling to get away - fighters and spectators alike. Gamora raced to hide behind a concrete block of venting pipes. "Sam? If you can fly onto one of them and hit the gun away from them that would be appreciated. There's too much confusion and too little visibility to approach them out of harm's way right now."
The fighters started hitting back, but they kept firing. This was going to be a blood bath.