The authorities in China have raided the Beijing office of the Mintz Group, an American corporate investigations firm, and detained all five of its Chinese employees, the company said March 24.

The New York Times reported that Mintz Group said in a statement that the authorities closed its operations in Beijing. The company has not been able to contact the employees since they were taken away.

It was unclear what the authorities’ objectives were in investigating the company, and the government did not respond to a request for comment. But the move highlighted the potential risks that firms involved in due diligence face in China as Xi Jinping, the country’s top leader, has repeatedly called for a greater emphasis on security and has tightened the ruling Communist Party’s grip on information.

The Mintz Group, which is based in New York, does due diligence work — background checks, asset tracing, and fraud and corruption investigations — for companies before they make acquisitions or other large investments.