One Direction pay tribute to a teenage girl who ran a fan club Twitter account, after she dies suddenly from a suspected heart attack.
Directioners descended into London's Leicester Square in their thousands this evening, for the world premiere of One Direction: This is Us.
One Direction's first movie premieres today ... but what does it have in store for the boyband's fans?
One Direction have paid tribute to teenage fan who died after suffering a suspected heart attack at school in Hounslow on Tuesday.
Magadelena Szablinska regularly met members of the band and ran a twitter fan site called 1DCrew.
Harry Styles tweeted 'It's incredibly sad to hear the news about Magda. She was so so lovely, I am thinking of her and her family'.
Twitter UK has confirmed more than 3.6 million tweets were posted on Twitter about One Direction and the One Direction world premiere in London.
One Direction is the most followed UK band on Twitter with more than 14 million followers.
Twitter revealed that the hashtag #1DMoviePremiere was used more than 1.9 million times over the last 24 hours.
Three of the band's members spoke to ITV London's Lucrezia Millarini on the red carpet.
Even with its long history of hosting film premieres, London's West End has never seen anything quite like this. Tens of thousands of fans have been cramming themselves into every corner of Leicester Square since first thing this morning, to get a glimpse of One Direction.
Sangeeta Kandola went to meet their dedicated army of fans.
Niall, Louis and Liam from One Direction have spoken to ITV News ahead of the world premiere of 'One Direction: This is Us' at Leicester Square in London.