An OpenAI executive told a federal jury Wednesday how Elon Musk once called him a "jackass" during a heated clash over AI safety.

Joshua Achiam, OpenAI's chief futurist, recalled the "pretty tense exchange" during testimony in the California civil trial between Musk and OpenAI CEO Sam Altman.

"He snapped and called me a jackass," Achiam testified.

Achiam said that around 50 to 60 employees had gathered during a February 2018 company all-hands meeting for a question-and-answer session ahead of Musk's planned departure from the startup he cofounded with Altman.

According to Achiam, then a research scientist at OpenAI, Musk said he was leaving because Tesla, Musk's electric car company, would soon compete with OpenAI for elite AI talent, creating a "conflict of interest."