Robert leaps over the desk and through the broken window, avoiding the glass and drawing his shotgun. The undead were beating the doors, and one had already managed to push one slightly open- the only "entrance" they'd need.
Robert blasted the lead infected. It shuddered, and went down- unfortunately, it was now propping the door open. The other infected hadn't made it in quite yet, but they were managing to stumble over the dead Infected fairly well.
Another shot. Robert kept blasting away, in hopes of thinning them out enough for it to be safe for the others if he had to back up.
Two more shots, emptying the Mossberg completely. Three infected now lay dead, effectively blocking the door from the shambling feet of the other undead, but also blocking any shot Robert had at them.
In this time, Rhea has managed to make a molotov. As Robert had managed the infected quite well, she held back for a bit without using it. She didn't have a clear throw anyway, and wouldn't want it to get near Robert. ((Molotovs, and incendiaries in general- work fast enough to be a good plan. The absolute maximum time a normal infected can survive while on fire is three turns of combat, and landing the molotov near them when it goes up does two, meaning that they'd be dead at the end of the turn. However, Robert can still say that bit earlier and be correct- because while it's alive, it's more damgerous. Among other things.))
Sarah is a bit calmed by how easily the zombies are dispatched, and isn't so shaky now. None are getting through, though, so...
One of the zombies starts gnawing on the door... and the door starts melting away in return.
"Oh, nice..." Oleg mumured, "Those bastards. Door isn't going to hold much longer. Looks like two of those acidic bastards."
Robert considers his options from here. The acidic zombies will breach the door completely in the time it would take for him to load his shotgun completely, and there's no way for him to take both with a single shot. The third infected means he won't be able to clearly target the acidic ones, meaning the rifle is a hit-or-miss application. Reloading the shotgun gives him a good chance at killing all three the next time he fires, but the door is toast. Switching to the Galil will give him a chance to kill one or two, but if an acidic one lives, the door is still toast.
Rhea shouts to Robert. "Use the molotov! It will repel them!"
Oleg shouts as well. "Hit them with it! You'll have time to put them down, and the fire should distract them enough to give you a clear shot! They might not feel pain like us, but the fungus definitely registers the fact that it's burning!"
Rhea tosses the unlit molotov to Robert, who catches it. Well, there's option three...
((To clarify, later stages of Infected can withstand fire for longer. Some are weaker to it, like the glass cannons (they aren't actually glass, nor do they have cannons, but it's fairly descriptive of how they operate.))