Saw blades are an environmental hazard in Team Fortress 2. Sawmill remains the only official map to feature them, however, the saw blades have appeared in some custom maps. Saw blades typically run in set grooves along either side of a capture point, usually in the center of a map. They move slowly enough that players can move out of harm's way, but are fast enough to catch sluggish or distracted players unaware, especially when they battle around the control point.
If a player is hit or touched by a saw blade, they will automatically be killed. Death occurs regardless of whether the player is ÜberCharged, using the Dead Ringer, or subject to any other protective buff. If a player is damaged and subsequently hit by a saw blade, they will receive one death point and the player(s) who damaged him will receive a "finished off" kill.
Sometimes, a saw blade model will move to another section of the map, most commonly causing players to see the top of it through the ground. This does not affect the ability for the saw blade to kill, and any players that walk in the path of where the saw blade should be will still be killed.
After a player dies by a saw blade, the player's blood will stain the saw blade until the next round.