https://www.gamespot.com/articles/fortnite-update-released-during-e3-2018-shopping-c/1100-6459673/

Right in the midst of E3, the next update for Epic's hugely popular battle royale game Fortnite has arrived, while the newly added Shopping Carts have now been removed. As outlined on Fortnite's website, the big new addition for update 4.4 is a new weapon in the form of the thermal scope assault rifle.

As its name suggests, this weapon can detect enemies by their heat signatures. It appears you'll no longer be able to safely hide in the bushes... The weapon is for the battle royale mode.