https://www.theverge.com/2018/4/3/17194552/youtube-shooting-twitter-hack-vadim-lavrusik-misinformation

As Twitter users searched for news about today’s shooting at YouTube headquarters, hackers were actively compromising a verified employee account to spread misinformation. In the midst of the attack, an unknown hoaxer hijacked a verified Twitter account belonging to Vadim Lavrusik, a product manager at YouTube, and used the high-profile account to implicate a YouTube broadcaster in the shooting.

The account hijacking seems to have taken place while Lavrusik and his colleagues were still near the scene of the attack: Lavrusik reported himself safe at 2:36pm PT, and the hoax tweets began posting just 20 minutes later.