New Delhi: In what can be called the biggest Twitter attack, accounts of many famous personalities like Barack Obama, Joe Biden, Elon Musk, Kanye West, Kim Kardashian, Bill Gates and others have been hacked.

Reacting to the same, Twitter CEO Jack Dorsey said that it is a tough day for them and they are trying to know what exactly happened. He said, "Tough day for us at Twitter. We all feel terrible this happened. We're diagnosing and will share everything we can when we have a more complete understanding of what exactly happened."

Dozens of high-profile accounts were hit in the scam, with each one posting a message that offered to pay a sender double any payment they made to a Bitcoin wallet address included in the tweet.

The Twitter hack took place in the wee hours of the morning. The message in the bitcoin scam tweets read, “We are giving back to our community. We support Bitcoin and we believe you should too! All Bitcoin sent to our address below will be sent back to you doubled!”

Former president Barack Obama, and presumptive Democratic presidential nominee Joe Biden were among the hacked accounts. Microsoft co-founder Bill Gates, Tesla CEO Elon Musk, Amazon CEO Jeff Bezos, entertainer Kanye West, and former New York City mayor Michael Bloomberg were also targeted, as were tech firms such as Apple and Uber.

Twitter Support acknowledged the hack around 3:00 am saying that it is investigating the issue. Since the hack caused bitcoin scam tweets to be sent out from accounts, Twitter disabled verified accounts from tweeting or even changing the password.

Unverified accounts could still tweet as the hack affected only verified accounts on Twitter. Verified accounts on Twitter have the blue tick on their profiles.

Hours later, Twitter Support updated that most accounts should be able to tweet again. Twitter is however still working on a fix and these functionalities may be limited again.