Grab the torch at the start (to scare the zombies), go into the first room pick up the documents, run through the small connecting room and grab the next documents. Push the heavy shelf away from the door (you need 3 people pushing to move it), go out of the door and down the right-hand side corridor. Pick up the second torch (the first one will be nearly spent by now) and go into the next door, grab the documents and go through the connecting door into the final room to grab those documents too. The exit will unlock so quickly before your torch runs out, go back to the right (either thru the rooms or out into the bottom corridor) and exit quickly.
Be careful to herd the zombies with the torches so they don't get stuck in corners near doorways - the survivors won't go near zombies even if they are running away!
Good luck!
They're coming!