CARACAS, Venezuela — Venezuelan President Nicolás Maduro was sworn in Friday to serve a third six-year term, extending his increasingly repressive rule until 2031 despite protests and credible evidence that his opponent won the election.

Venezuela’s legislative palace, where he was sworn in and delivered a fiery speech, was heavily guarded by police, military and intelligence officers. Crowds of people, many sporting pro-Maduro T-shirts, gathered in adjacent streets and a nearby plaza.