Buenos Aires, Argentina - One Direction star Niall Horan has paid tribute to Liam Payne after the late singer's tragic death.

On Friday, the Irish artist shared a heart-wrenching tribute to Payne via Instagram following the 31-year-old's unexpected death.

The pop star tragically died on October 16 after falling multiple stories from his balcony at the CasaSur Palermo Hotel, Policía Federal Argentina confirmed.

"I'm absolutely devastated about the passing of my amazing friend, Liam. It just doesn't feel real," Niall penned in the post, which first featured a snap of the pair in their younger years.

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He continued, "Liam had an energy for life and a passion for work that was infectious. He was the brightest in every room and always made everyone feel happy and secure."

Niall saw Liam earlier this month at his October 2 show in Buenos Aires amid his ongoing The Show: Live on Tour.

The Strip That Down hitmaker was captured dancing and singing along with his girlfriend, Kate Cassidy, at Niall's concert.

Liam later shared a pic of himself with Niall to Snapchat and captioned the post, "Reunited."

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The Heaven singer reflected on their reunion in the caption, writing, "I feel so fortunate that I got to see him recently. I sadly didn't know that after saying goodbye and hugging him, I would be saying goodbye forever. It's heartbreaking."

Horan concluded the post, "My love and condolences go out to Geoff, Karen, Ruth, Nicola and of course his son Bear. Thank you for everything, Payno. Love you brother."

Niall and the other three members of One Direction – Harry Styles, Zayn Malik, and Louis Tomlinson – first broke their silence on Thursday with a joint statement mourning their late bandmate.