The font for that text is Pricedown. If you want to use it in your scripts, you'd have to use the following code:
[pawn]GameTextForAll("~b~Killing Spree!");[/pawn]
Or, if you want to have it closer to the bottom of the screen, you need to add blank lines of text by using the code \x10, like this:
[pawn]GameTextForAll("~b~\x10 \x10 \x10 \x10Killing Spree!");[/pawn]