On Friday, Twitter CEO and co-founder Jack Dorsey's Twitter account was compromised in what has now been confirmed as a hack. Yesterday, the account "@jack" posted a stream of tweets including racial slurs, profanity and anti-semitic messages, which a group of hackers called the Chuckle Squad has now claimed responsibility for.

The tweets managed to stay up for 10 minutes before being taken down and subsequently Twitter tweeted “the account is now secure, and there is no indication that Twitter’s systems have been compromised.”

This is not the first time Dorsey's Twitter has been hijacked. Back in 2016, the Saudi Arabian hacker group OurMine posted up a message about “testing your security” from his account. This time Twitter is blaming the security breach on Dorsey’s cellular service provider: “the phone number associated with the account was compromised due to security oversight by the mobile provider.” It seems the hackers used a service named Cloudhopper to send the tweets through text messages.

It’s still unclear who the members of the Chuckle Squad are and what their motivations were.