The official Twitter accounts of Apple, Elon Musk, Jeff Bezos, Joe Biden and others were hijacked on Wednesday by scammers trying to trick people into sending them Bitcoin. In a massive hack, the list of compromised accounts grew rapidly to include Barack Obama, Uber, Microsoft co-founder Bill Gates, Kanye West, bitcoin specialty firms and many others. Among the cryptocurrency accounts hacked were those of Bitcoin, Ripple, Coindesk and Coinbase. Posts, most of which were deleted quickly, were fired off from the high-profile accounts telling people they had 30 minutes to send $1,000 in Bitcoin to be sent back twice as much. "This is a scam, do not participate," Gemini cryptocurrency exchange co-founder Cameron Winklevoss warned in a tweet from his official account. "This is the same attack/takeover that other major crypto Twitter accounts are experiencing. Be vigilant." Comments and posts at Twitter indicated thousands of dollars in Bitcoin might have been sent to the scammers' digital account. Twitter acknowledged the situation at 1.45am UAE time on Thursday. The cause of the breach was not immediately clear, but the scale and the scope of the problem suggested it was not limited to a single account or service. Shares of Twitter tumbled nearly 4 per cent in trading after the market close. The tech giant said that it was aware of a “security incident impacting accounts on Twitter". It said it was investigating and working to fix it, and promised an update shortly. "Given the accounts that got hacked more recently [Apple, Uber, Gates, Musk, etc], I am now leaning towards this being an internal compromise of a Twitter system, not an API attack from a social aggregator service," Bitcoin authority and author Andreas Antonopoulos said in a tweet. A version of the scam invited people to click on a link at which they would be exploited.