Her death comes shortly after Louis released a new song titled "Two of Us" about him and his mom which included the heartbreaking lyrics: "You'll never know how much I miss you/the day that they took you/I wish it was me instead".
The tragedy is a huge blow for Louis, who lost his mother, Johannah, to cancer in December, 2016. Felicite - who was known to friends and loved ones as Fizzy - was an aspiring fashion designer and influencer with 1.3million Instagram followers.
Singer Charlie Puth wrote: "Prayers to Louis Tomlinson".
Sources tell TMZ, the devastated singer was very close to his sister and is now spending time with family. I can't imagine how hard it is right now.
Rockets Fired From Gaza At Tel Aviv, Explosions Heard: Israeli Military
Thursday's incident is the first time since the 2014 war that rockets from Gaza have come anywhere near Tel Aviv . The Palestinian Islamic Jihad terror group is thought to be behind the attack, said sources in the Gaza Strip.
Dancing On Ice star Brian McFadden continued: "This is so sad".
X Factor winners Rak-Su also offered their prayers for the family. "You're not on your own in this", before assuring Louis that people are pulling for the Tomlinson family. A person who was with her at the time called 999 (the United Kingdom version of 911), and emergency responders quickly arrived on the scene.
In a statement, Scotland Yard said: "Police were called by London Ambulance Service at 12.52 on Wednesday March 13 to a residential address ... following reports of a female in cardiac arrest".
On January 30, she posted a picture of a row of tattoos on her forearm, which she said were the initials of all her siblings.
Louis was meant to perform at a Comic Relief event tonight in London, however, his apperance was cancelled by his publicist.