Joe Biden, Elon Musk, Jeff Bezos and other high-profile Twitter accounts appeared Wednesday to be the target of organized hacks across the social media platform to offer fake bitcoin deals.

Former president Barack Obama, Microsoft co-founder Bill Gates and corporate accounts for both Uber and Apple also appeared to be targeted, and at least one Silicon Valley entrepreneur warned of a wider-spread attack. The tweets all instructed people to send cryptocurrency to the same bitcoin address. The tweets were removed shortly after being posted, and Twitter spokeswoman Aly Pavela said the company was investigating.

New tweets that appeared to be hackers were still being posted more than an hour after Musk’s account tweeted the scam message.

A now-deleted tweet from Tesla CEO Musk’s account said, “Feeling greatful, doubling all payments sent to my BTC address! You send $1,000, I send back $2,000! Only doing this for the next 30 minutes.”

His account continued to tweet similar posts as they were deleted.

Screenshots show that Democratic presidential candidate Joe Biden was also a target of the hack. His account apparently tweeted out the same bitcoin wallet address.

“This is a SCAM, DO NOT participate!” Cameron Winklevoss, a bitcoin investor and co-founder of Gemini.

Gemini’s account was hacked earlier in the day, Winklevoss tweeted, despite the account using two-factor authentication to secure it.

Amazon chief executive and Washington Post owner Bezos’ account tweeted, “I have decided to give back to my community.” The tweet said it would be limited to $50 million.

Apple’s and Uber’s corporate accounts also appear to have fallen victim to the hack. Uber posted a tweet that read, “Due to Covid-19, we are giving back over $10,000,000 in Bitcoin! All payments sent to our address below will be sent back doubled.”

Uber confirmed in a tweet that its account had been hacked.

“Like many others, our @Uber account was hit by a scammer today. The tweet has been deleted and we’re working directly with @Twitter to figure out what happened,” the company’s communication team tweeted.

Representatives for Musk, Bezos and Gates and Biden did not immediately respond to a request for comment. Apple did not immediately respond to a request for comment.