The first person to die in the short story "The Sniper" is known as the man in the armored car.  He poked his head out of the top turret in order to speak to the old woman.  She is an informer that is telling the man where the sniper is located.  The man in the armored car was shot by the sniper and slumped over the turret. 

The sniper raised his rifle and fired. The head 35 fell heavily on the turret wall.

The second person to die is the old woman that was informing on the sniper's location.  She was shot and killed immediately after the man in the turret as she was running to escape. 

The woman darted towards the side street. The sniper fired again. The woman whirled round and fell with a sudden shriek into the gutter.

The last man to die is the enemy sniper that was located in the next building over.  The main character sniper shot him with a revolver.  As he was dying from the bullet wound, he fell over the edge of the building.  

Then the dying man on the roof crumpled up and fell forward. The body turned over and over in space and hit the ground with a dull thud. Then it lay still.

In all, three people died in the story.