Last week, the CEO of Twitter, Jack Dorsey’s account was hacked through Twitter’s SMS service. Consequently, Twitter has temporarily “turned off the ability to tweet via SMS.”

In a series of tweets posted from Twitter’s official handle yesterday, the company said, “We’re taking this step because of vulnerabilities that need to be addressed by mobile carriers and our reliance on having a linked phone number for two-factor authentication (we’re working on improving this).”

We’re taking this step because of vulnerabilities that need to be addressed by mobile carriers and our reliance on having a linked phone number for two-factor authentication (we’re working on improving this).

— Support (@Support) September 4, 2019

Twitter further said that the service would soon be reactivated in markets that depend on SMS for reliable communication while work on a longer-term strategy continues.

The hackers of Jack’s account reportedly identified as the Chuckling Squad gained access to the account which has more than 4 million followers and tweeted offensive and racist comments.

The Chuckling Squad allegedly hacked the account using a method called “SIM hacking” that enables hackers to trick a mobile carrier into transferring the target’s phone number to another phone. The hackers, having gained access, then use Twitter’s text message service to tweet using the victim’s account.

This isn’t the first time Jack’s account would be hacked; in 2016, his account was allegedly hacked by a group — OurMine — that also attacked other tech leaders including Mark Zuckerberg, CEO of Facebook.

Just barely a week after Jack’s account was hacked, Twitter accounts of other public figures and users have also been reportedly compromised.

It’s make me so sad to see my old twitter hacked @KerrivahHeard and there’s zero @Twitter has done to help 😭. I’m so sad. All my journalism connections from 2011 until was on that account 🤦🏾‍♀️.

— $kee (@mediamavenkh) September 5, 2019

However, it is unclear if the same group that hacked Jack’s account is responsible for these recent hacks.

The tweeting via SMS service has been used to post tweets and receive notifications from Twitter since the inception of the social media platform, and following Jack’s account hack, it remains to be seen how long this suspension will last.