Eulalio Tordil, a federal security officer, faces charges of first-degree murder over a series of shootings last week in Prince George's and Montgomery counties in Maryland. In cases like this, when shootings occur over a period of time or a wide area, a reporter will have the impulse to call them a spree.
Don't do it.
I have said elsewhere that a reporter with a thesaurus is like a toddler with a loaded handgun. But while a thesaurus can mislead the writer looking for an exact synonym, it can be instructive by indicating the web of associations for a particular word.
In the case of spree, a check with a thesaurus will turn up frolic, gambol, lark, romp, caper, and high jinks (or hijinks, if you prefer). The playful context does not immediately suggest fatal shootings.
Spree is also associated with drinking, and you will find binge and bender linked to it. To embark on a spree is, as the slang of my youth had it, to go on a toot. Less light-hearted than high jinks, but still far short of homicide.
If you want a strongly evocative word for a series of fatal shootings, let me suggest rampage.