Hong Kong riot police launched tear gas and ejected angry protesters from the city’s legislature building Monday, while perhaps half a million more protesters marched peacefully.

It all unfolded on the 22nd anniversary of Hong Kong’s return to Chinese rule as a semi-autonomous territory.

There have been protests for weeks over the territorial government’s move to allow extraditions to China, as well as deep concerns about how much autonomy Beijing is willing to allow the city’s residents going forward.

The escalation has brought Hong Kong into unprecedented and uncertain territory, and represents the biggest test of Beijing’s grip over the global financial hub and the status under which it operates,” reports the Washington Post.

The violence was triggered when a large group of protesters broke off from the main line of marchers, smashing their way into the Legislative Council building, vandalizing the council headquarters and tearing down powers of pro-Beijing officials when police appeared to pull back.

The pullback didn’t last long.

Hundreds of riot police with shields and helmets fired tear gas after midnight [Tuesday, Hong Kong time] at dozens of demonstrators who had set up barricades on the roads around the city’s legislative complex, after a core group of protesters had occupied the building for three hours,” reports the New York Times.

The protest, says the Times, turned into “a broad repudiation of Chinese rule, with demonstrators tearing up copies of the Basic Law, a mini constitution that took effect in 1997 and governs Hong Kong’s relations with Beijing, and calling for free and direct elections.”

Early on Monday, before the main demonstrations began, riot police used batons and pepper spray to beat back protesters at a different site — near a flag-raising ceremony led by the city’s chief executive, Carrie Lam.

Some protesters hope to force Lam to negotiate with them directly, in hopes of avoiding an even worse eruption.

If this is left to the police and Beijing to solve, we will face the greatest tragedy we’ve seen in 22 years” of Chinese rule, Eddie Chu, a pro-democracy member of the legislature, told reporters.