One Direction star Louis Tomlinson’s 18-year-old sister died suddenly of an apparent heart attack, according to multiple media reports.

British media report that Felicite Tomlinson died on Wednesday after collapsing at her London apartment.

Felicite had a large following on Instagram, where she sometimes posted photos of Tomlinson and their other siblings. Their mother, Johannah Deakin, died from leukemia in 2016 at the age of 43.

Many celebrities and One Direction fans have expressed shock at Felicite’s sudden death and offered their condolences to Tomlinson on social media.