A 21-year-old son of an NFL assistant coach has taken responsibility for prank-calling former University of Colorado quarterback Shedeur Sanders during the NFL Draft late last week.

I made a tremendous mistake,” Jax Ulbrich wrote on Instagram. “Shedeur, what I did was completely inexcusable, embarrassing, and shameful. I’m so sorry I took away from your moment, it was selfish and childish.

Falcons issue a statement regarding the Shedeur Sanders prank phone call. Jax Ulbrich, the 21-year-old son of Falcons defensive coordinator Jeff Ulbrich, has apologized to Sanders. pic.twitter.com/cEt31mC7en