It's zombie killing season.

The normal question, the first question is always; are these cannibals? No, they are not cannibals. Cannibalism in the true sense of the word implies an interspecies activity. These creatures cannot be considered human. They prey on humans. They do not prey on each other, that's the difference. They attack and they feed only on warm human flesh. Intelligence? Seemingly little or no reasoning power, but basic skills remain a more remembered behaviors from normal life. There are reports of these creatures using tools. But even these actions are the most primitive, the use of external articles as bludgeons and so forth. I might point out to you that even animals will adopt the basic use of tools in this manner. These creatures are nothing but pure, motorized instinct. We must not be lulled by the concept that these are our family members or our friends. They are not. They will not respond to such emotions.

(Yes, I am well aware that this quote from Dawn of the Dead doesn't FULLY apply because L4D's zombies aren't flesh eating, but I find that it's still appropriate)