Harry Styles, Niall Horan, Louis Tomlinson and Zayn Malik have released both joint and individual statements following Payne's death on Oct. 16 at age 31. The U.K.-based group hit it big in 2010 and officially split in 2016 amid internal strife and individual ambitions.

"We're completely devastated by the news of Liam's passing. In time, and when everyone is able to, there will be more to say. But for now, we will take some time to grieve and process the loss of our brother, who we loved dearly. The memories we shared with him will be treasured forever. For now, our thoughts are with his family, his friends, and the fans who loved him alongside us. We will miss him terribly. We love you Liam," the members of One Direction said on the group's Instagram account.

One by one, each singer then shared a photo memory and personal message about their friend "Payno," who died in Buenos Aires from a fall from his hotel balcony.

Styles shared a photo of Payne, from behind, performing in front of a packed stadium.

He wrote that Payne's "greatest joy was making other people happy" and called it an honor to witness. He said Payne "lived wide open, with his heart on his sleeve" and "an energy for life that was infectious. He was warm, supportive, and incredibly loving."

The years they spent in 1D "will forever remain among the most cherished years of my life. I will miss him always, my lovely friend," Styles wrote.

Malik -- who departed the group first in 2015, and had tension with Payne -- posted a photo of them asleep against each other in their early 1D days.

He addressed their drama, writing, "Even though we butted heads," he "always secretly respected" Payne for being "headstrong, opinionated" and "telling people when they were wrong." He said the "Teardrops" singer was the "most qualified" member of the group, admitting at the start, "l was a novice child with no experience and you were already a professional."

Malik thanked Payne for supporting him "through some of the most difficult times in my life."

He wrote that he thought there would be "many more conversations" between them in the years ahead to work things out. "I lost a brother when you left us and can't explain to you what I'd give to just give you a hug one last time and say goodbye to you properly and tell you that I loved and respected you dearly," he wrote.

Tomlinson shared a photo of them together on stage. Payne's arm is wrapped around him.

He wrote that he was "beyond devastated" to lose his "brother" and a "best friend," who was "somebody I looked up to everyday, such a positive, funny, and kind soul."

Tomlinson talked about Payne's talents, calling him the "most vital part of One Direction," and his songwriting abilities. He said they would still talk on the phone for hours and discussed getting back in the studio together to "recreate the writing chemistry we had built up."

He ended with a message to Payne, including telling him that if his 7-year-old son "Bear ever needs me I will be the Uncle he needs in his life and tell him stories of how amazing his dad was."

Horan had just had a mini-reunion with Payne, who came to Buenos Aires to see him perform on Oct. 2. He posted a sweet throwback of them mugging for the camera.

He wrote about Payne's "energy for life and a passion for work that was infectious." He called him "the brightest in every room" and the person who "always made everyone feel happy and secure." He said getting to "live out our wildest dreams together" is something he'll forever "cherish."

Horan said he felt "so fortunate that I got to see him recently. I sadly didn't know that after saying goodbye and hugging him that evening, I would be saying goodbye forever. It's heartbreaking."

An investigation is underway into Payne's death. Local authorities have said they think it's related to "substance abuse." His hotel room at the CasaSur Palermo Hotel was in "total disorder" and the hotel manager said in the 911 call that he feared for Payne's life, specifically noting that the star was in a room with a balcony.

When emergency services arrived at the scene at 5:11 p.m. local time, seven minutes after the 911 call, Payne's body was found in the inner courtyard of the hotel. He was pronounced dead on the scene.