That could cause liability.
Setting a trap can be illegal too. Manslaughter is not out of the question.
Don't set traps. Just saying....
If you think tear gas is going to kill people then how about an air-horn so it can be noticed when someone is stealing your private property and infringing on the right to free speech?
Or is there something you want to nit-pick in my direction (rather than the perpetrators) about that too?