Twitter is investigating a security breach which has seen many high profile celebrities have their profiles hacked. Elon Musk, Joe Biden, and Bill Gates were amongst the individuals who’s accounts were breached.

Posts trying to trick people into sending hackers the cryptocurrency Bitcoin were tweeted by the official accounts of Apple, Uber, Kanye West, Bill Gates, Barack Obama and many others on Wednesday.

“We detected what we believe to be a coordinated social engineering attack by people who successfully targeted some of our employees with access to internal systems and tools,” Twitter said.

“They used this access to take control of many highly-visible… accounts,” the company said, adding that it was investigating “what other malicious activity they may have conducted or information they may have accessed.”

Read More: France 24