Kim Zolciak-Biermann, Daughter Brielle Mourn Death Of Family Friend In Heartbreaking Posts

"Real Housewives of Atlanta" alum Kim Zolciak-Biermann and her daughter Brielle are grieving the loss of a close family friend, Ethan McCallister.

On Saturday, Kim and Brielle took to social media to pay tribute to McCallister, who had died earlier that day. The 42-year-old "Don't Be Tardy" star shared photos of her with their friend on Instagram and recounted some of their happy moments together in her caption.

"We will miss your huge beautiful smile, constant jokes, cowboy boots and infamous shirts. You were always the life of the party!!" Kim wrote. "One of the most genuine kind hearted people I have ever known [red heat emoji] Always willing to help anyone anywhere. We love you Ethan and I will make sure justice is served."

The "RHOA" alum said after her friend was killed in a hit and run early Saturday while out in Atlanta, Georgia. She added that a TrackHawk Grey with a yellow accent hit McCallister.

Kim urged her followers to call Atlanta police if they know anything about the incident. She also shared a GoFundMe link where people can donate to support his surviving family.

Kim's daughter, Brielle, was also heartbroken over McCallister's death. She wrote on Instagram that she considered him her best friend and that she was "sick to my stomach" over his passing.

"Ethan.... i can’t believe I’m even writing this. I’m sick sick sick to my stomach. You are my happiness my joy my light in this very dark world.. the life of the party and the sweetest soul I’ve been blessed to know," Brielle wrote. "You are my best friend. My heart. My everything. There will never be another you. Ever ever ever. You came into this world with 1 mission... make people smile. You were damn good at it too. There was never a moment i wasn’t laughing with you!!"

The 24-year-old added that they had not spent a weekend apart all year. "God i love you ethan. I really really do. I can’t wait to see you again," Brielle concluded her post.

Atlanta police told 11Alive that McCallister was taken to the hospital, where he was pronounced dead. Authorities said the driver did not stop and kept going after hitting him. Police are currently looking for the driver.