A number of high-profile journalists and commentators were suspended by Twitter on Thursday night with no warning, and without any obvious sign of what caused the suspensions.

Among those suspended were former MSNBC and ESPN host Keith Olbermann, and CNN correspondent Donie O’Sullivan. Other journalists suspended on Thursday included New York Times reporter Ryan Mac, Washington Post reporter Drew Harwell, Matt Binder of Mashable, and freelance journalist Aaron Rupar.

It is not immediately clear why Twitter, now owned by billionaire Elon Musk, suspended them, though some all of the journalists covered and have been in some cases critical of Musk. Olbermann, shortly before being suspended, tweeted a link to a Mastadon Social account that tracked Musk’s private jet (the Elon Musk jet account had been active on Twitter, until Musk changed the terms of service earlier this week to ban accounts that share real-time location information about private individuals).

“The impulsive and unjustified suspension of a number of reporters, including CNN’s Donie O’Sullivan, is concerning but not surprising,” a CNN rep tweeted. “Twitter’s increasing instability and volatility should be of incredible concern for everyone who uses the platform. We have asked Twitter for an explanation, and we will reevaluate our relationship based on that response.”

Alex Heath, an editor at The Verge, said that Twitter’s head of trust and safety suggested to him that the suspensions were related to the new policy change.

“Same doxxing rules apply to ‘journalists’ as to everyone else,” Musk tweeted Thursday in response to a tweet about the suspensions.

Musk, who acquired Twitter in October, had justified his purchase based on the idea that he would return “free speech” to Twitter, and had handed over internal Twitter correspondence about Jan. 6 the banning of former President Trump to journalists like Matt Taibbi and Bari Weiss, who reported on them to shine light on the internal deliberations at the company during those decisions.