The official Twitter accounts of Apple, Elon Musk, Jeff Bezos and others were hijacked on Wednesday by scammers trying to dupe people into sending cryptocurrency bitcoin in the hope of doubling their money.

Twitter posts, which have been deleted, were fired off from an array of high-profile accounts telling people they had 30 minutes to send $1,000 in bitcoin in order 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 at Twitter.

“This is the same attack/takeover that other major crypto twitter accounts are experiencing. Be vigilant!”