from his lookout point the doctor could see across most of the shopping district, and he could also see the amount of infected moving in towards the pet shop. he let a nervous laugh escape him "why can no one just keep quite" he sighed and ran down the ladder grabbing a few extra mags popping one in the gun as he approached the ladder. he climbed up to his lookout point and aimed at the few infected approaching, one was coming out an alleyway, one down a street and finally one near a pet shop. he fired at the one closest to the pet-shop but the bullet went wide and hit the lock on the front door, he re-aimed and took the shot nailing the guy in the head, he went down like a sack of bricks. 

he re-aligned his sights on the alley walker, calmed his breathing, and fired the shot hit his leg. the mucil exploded and he fell behind a car. 

he then aimed at street, the bullet tore through his splean and fired another and it smashed his brain out the other-side.