How many people are on rooftops in "The Sniper?"

At the beginning of the story "The Sniper," there is one sniper on the roof top." The Sniper has been positioned atop a roof in Dublin. His role in the battle is not clear, but the streets of Dublin are awash with fighting, and he likely has been assigned to shoot enemy targets in the streets below." He is careless and his cigarette gives away his position.  A soldier climbs up on the roof across from the sniper.  When the sniper shoots a soldier and an older woman in the street below, the soldier on the roof across from him is able to get a bead on him and shoots.  The sniper is wounded and must figure a way out of his situation.  Altogether there are two people on the rooftops.