Elon Musk shared a painful memory on Twitter.

Musk took to a far-right theorist, Alex Jones, who claimed one of the worst mass murders in American history was fake.

Musk said he felt the pain of losing a child:

"My first child died in my arms. I felt the last heartbeat. I have no mercy for anyone who would use the death of children for profit, politics or fame," Musk wrote.

Elon Musk attached this comment to Twitter's decision to no longer allow Alex Jones to post about the event.

Musk's first son, named Nevada Alexande, passed away in 2002 from sudden infant death syndrome (SIDS).