The popular battle royale game is known for its large, live showpiece events, and developer Epic Games had previously confirmed that an event known as "The End" would take place on October 13.
Those who logged on to Fortnite on Sunday night saw the virtual island where the game takes place hit by a meteor shower before the entire map appeared to be sucked into a black hole.
Since then, anyone logging on to the game has been presented with a live stream of the black hole and no way of playing.
As part of a complete blackout, the official Fortnite Twitter account has also deleted all of its tweets apart from a live stream of the black hole. It has been retweeted more than 120,000 times.
The game - which sees up to 100 competitors battle to be the last player standing - is broken up into seasons which last several months, with the start of each new season marked by in-game events.
Previous large Fortnite events have included a meteor shower, a rocket launch, and a fight between a giant robot and a monster taking place across the map earlier this year.
Since its initial release in 2017, Fortnite has become one of the world's most popular video games.
The game held its own inaugural World Cup Finals earlier this year, where more than 100 players competed for a total prize pot of £24 million.