British investigators on Friday night searched the London offices of Cambridge Analytica, the data-analytics company that harvested data from 50 million Facebook users to develop psychological profiles on behalf of political campaigns, including that of President Trump.

About 20 investigators from Britain’s data watchdog, the Information Commissioner’s Office, descended on the company’s offices on New Oxford Street after obtaining a search warrant from the High Court.

“We are pleased with the decision of the judge, and the warrant is now being executed,” the office of the information commissioner, Elizabeth Denham, said in a statement. “This is just one part of a larger investigation into the use of personal data and analytics for political purposes. As you will expect, we will now need to collect, assess and consider the evidence before coming to any conclusions.”

Last Saturday, the same day The New York Times and The Observer of London published a detailed look at the company’s use of Facebook data, Ms. Denham’s office announced an investigation into “the circumstances in which Facebook data may have been illegally acquired and used.”