Leeds confirmed emergency services had responded to an incident at Stamford Bridge, after reports that a fan fell from the top tier of the Shed End.
The Championship side took more than 5,000 supporters to west London for the FA Cup fifth-round tie, as they gave Chelsea real scare before Conor Gallagher scored in the 90th-minute to hand the Blues a 3-2 win.
Leeds took the lead in the eight minute, as Mateo Joseph, who scored both of his side’s goals, pounced on an error from Axel Disasi and Moises Caicedo.
It is reported that a Leeds supporter fell into the lower tier of the stands while celebrating. Police officers and medics were quickly on the scene.
The match continued without delay, but Leeds issued a response after the game to confirm an incident had taken place.
A statement from the club said: "Leeds United can confirm an incident involving a Leeds United supporter occurred in the Shed End of Stamford Bridge during the first-half of tonight’s FA Cup game.
“The incident is being investigated and is in the hands of the emergency services.
“We will be making no further comment at this time."
Leeds boss Daniel Farke said after the match: "Football is unbelievably serious but health is more important than football results.
“We send our best wishes and prayers and our fingers are crossed that it is not too serious."
