Story highlights Ex-"Umbrella Movement" leader Joshua Wong arrested ahead of Chinese leader's arrival

President Xi Jinping to visit Hong Kong as city marks 20 years under Chinese rule

Hong Kong (CNN) Chinese President Xi Jinping will arrive in Hong Kong amid unprecedented security Thursday, his first official visit as leader, as the city marks 20 years of Chinese rule on Saturday.

Xi's plane is expected to touch down at noon local time, and he will then drive into the city in a heavily protected motorcade.

Protests broke out late Wednesday ahead of Xi's highly choreographed visit, with activists storming Golden Bauhinia Square -- the site of an official flag-raising ceremony later this week -- and occupying it for several hours before police removed them.

The protesters were led by former "Umbrella Movement" leaders Joshua Wong and Nathan Law, both of whom were carried off the square by police and arrested on public nuisance offenses.

Activist Joshua Wong is arrested Wednesday in Hong Kong's Golden Bauhinia Square.