AI expert Andrew Ng announced today that he’s leaving Chinese internet giant Baidu which has been betting heavily on AI for its business revival. Andrew didn’t mention his future plans in his announcement.

Baidu’s response to TechNode’s inquiries on this matter confirmed Ng’s resignation, “The news was released by Andrew himself on Medium first, Baidu has retweeted his posts with our thanks and wishes.”

Andrew took the helm of Baidu’s AI unit in 2014 as Chief Scientist. Before joining Baidu, Andrew built his reputation in the AI industry as the man behind Google Brain, Google’s deep learning arm. He’s also a Stanford University academic and co-founder of education platform Coursera.

Under his leadership, Baidu’s AI group has grown to roughly 1,300 people, which includes the 300-person Baidu Research.

“Our AI software is used every day by hundreds of millions of people. We have had tremendous revenue and product impact, through the many dozens of AI projects that support our existing businesses in search, advertising, maps, take-out delivery, voice search, security, consumer finance and many more,” he said in the announcement.

Wang Haifeng, vice president of Baidu, has been named as head of Baidu’s AI department, reporting directly to Lu Qi, former Microsoft executive and AI expert who joined Baidu as president and COO earlier this year. But it’s still not clear who at Baidu will take Ng’s title of chief scientist.

Andrew’s resignation is a huge blow for Baidu, which has been pushing aggressively for its AI initiative with growing R&D investment, investments in AI startups, such as Alexa-like service Raven Tech, and plans to build a national AI lab.