Thomas Ayad, a friend and former colleague of Justin Bieber, was killed in the Paris terror attacks Friday, and Bieber offered a tribute to the United Music Group exec Monday on Twitter, Us reports. "Still thinking about Paris and my friend Thomas that we lost in the tragedy," Bieber wrote; Ayad was killed at the Eagles of Death Metal show in the Bataclan theater. "He was a part of the team for years and I wish I would've had more time to thank him. Make sure to appreciate people while you have them. Thanks Thomas for everything you did for me. You are appreciated and missed. Thoughts and prayers are with your family & friends #PrayForParis." (The Eagles of Death Metal merch manager was also killed.)