UFC legend Francis Ngannou revealed Monday that his 15-month-old son, Kobe, died on Saturday.

"I was my best self next to him, and now I have no clue of who I am," he wrote. "Life is so unfair to hit us where it hurts the most."

He also posted another message on social media Monday, while Conor McGregor was among those who reached out and expressed their sympathies:

Ngannou's coach, Eric Nicksick, responded by asking fans to "please keep Francis and his family in your heart, and may this be a reminder of the fragility of life. Say 'I love you' more often, tomorrow isn't guaranteed."

The details of Kobe's death were not publicly made available.

Ngannou became a household name as a heavyweight champion in the UFC but recently switched to boxing. He lost his debut fight against Tyson Fury in a matchup that was closer than expected and then lost to Anthony Joshua in his second professional boxing match on March 8.