The short message service Twitter has blocked the accounts of several journalists.
Reporters from the New York Times, the Washington Post and CNN are among those affected.
They all reported this week that Twitter had shut down an account that uses publicly available data to track Elon Musk's private jet flights.
Musk, who describes himself as a "free speech absolutist," took over Twitter in a bid to end censorship.
In a tweet, he accused the journalists of "doxxing" - i.e. the publication of personal data that would have endangered the safety of his family.
The "New York Times" described the blocking of accounts as questionable and called for further explanations.
"I wasn't warned.
I have no email or communication from the company as to the reason for the suspension," New York Times reporter Ryan Mac tweeted from a new account.
“I cover Elon Musk and his companies on Twitter.
And I will continue to do so.” CNN was also outraged.
"The sudden and unwarranted suspension of journalists, including CCN's Donie O'Sullivan, is worrying - but not surprising," the TV network said.
"Twitter's increasing instability and volatility should raise major concerns for anyone using the platform."