Twitter accounts of prominent figures, including Biden, Musk and Obama, compromised in major hack.
Accounts of Uber and Apple also appear to have been compromised as part of scam instructing followers to transfer cryptocurrency
Billionaires Elon Musk, Jeff Bezos and Bill Gates are among many prominent US figures targeted by hackers on Twitter in an apparent Bitcoin scam.
The official accounts of Barack Obama, Joe Biden and Kanye West also requested donations in the cryptocurrency.
"Everyone is asking me to give back, and now is the time," a tweet from Mr Gates' account said. "You send $1,000, I send you back $2,000."
The tweets were deleted just minutes after they were first posted.
Twitter took the extraordinary step of stopping many verified accounts marked with blue ticks from tweeting altogether.
There were reports that password reset requests were also being denied.
Dmitri Alperovitch, who co-founded cyber-security company CrowdStrike, told Reuters news agency: "This appears to be the worst hack of a major social media platform yet."
Twitter said it was looking into the incident and would issue a statement soon.
On the official account of Mr Musk, the Tesla and SpaceX chief appeared to offer to double any Bitcoin payment sent to the address of his digital wallet "for the next hour".
"I'm feeling generous because of Covid-19," the tweet added, along with a Bitcoin link address.
One such tweet from Musk's account was deleted, only for another one to appear, then a third.
As well as rapper Kanye West, his wife, reality TV star Kim Kardashian, former US President Obama, Mr Biden, who is the current Democratic presidential candidate, and media billionaire Mike Bloomberg, major companies Uber and Apple were targeted.
The Biden campaign said Twitter had "locked down the account within a few minutes of the breach and removed the related tweet".
A spokesman for Bill Gates told AP news agency: "This appears to be part of a larger issue that Twitter is facing."