Riot police surrounded Hong Kong’s parliament early on Monday after what had been a peaceful million-strong protest against an extradition bill descended into running clashes between police and protesters, Trend reports citing Reuters.

Several hundred riot police armed with batons, shields, tear gas guns and pepper spray sealed off the Legislative Council as a similar number of protesters charged their lines shortly after midnight, Reuters witnesses said.

Police used batons and fired pepper spray at protesters, who still managed to close off part of a nearby road. Several people on both sides appeared to be injured, and ambulances were called. Metal barriers were left twisted and torn in the clashes.

The Legislative Council is where debates will start on Wednesday to pass a new government bill that will allow suspects wanted in mainland China to be sent across the border for trial.

Earlier on Sunday, hundreds of thousands had jammed Hong Kong’s streets to protest the bill in the biggest demonstration in years. Many said they feared it put the city’s vaunted legal independence at risk.

The rallies - and the violence - plunge the global financial hub into a fresh political crisis, with marchers and opposition leaders demanding the bill be shelved and that the city’s Beijing-backed Chief Executive Carrie Lam resign.

After seven hours of marching, organizers estimated 1,030,000 people took part, far outstripping a demonstration in 2003 when half that number hit the streets to successfully challenge government plans for tighter national security laws.

A police spokesman said police estimated 240,000 were on the march “at its peak”.