Tens of thousands of demonstrators in Hong Kong surrounded the city’s legislature on Wednesday, forcing it to postpone a second round of debate on an extradition bill that would allow people to be sent to mainland China for trial.

The protesters, most of them young people dressed in black, erected barricades as they prepared to hunker down for an extended occupation of the area, in scenes reminiscent of pro-democracy “Occupy” protests that rocked the city in 2014.

Protesters rallied in and around Lung Wo Road, a main east-west artery near the offices of embattled Hong Kong Chief Executive Carrie Lam, as hundreds of riot police warned them to stop advancing.

“We won’t leave till they scrap the law,” said one young man wearing a black mask and gloves.

“Carrie Lam has underestimated us. We Won’t let her get away with this.”

Lam has vowed to press ahead with the legislation despite deep concerns in the Asian financial hub, including among business leaders, that it could undermine freedoms and investor confidence, and erode its competitive advantages.

Opposition to the bill on Sunday triggered Hong Kong’s biggest political demonstration since its handover from British to Chinese rule in 1997 under a deal guaranteeing it special autonomy.

The government said debate on the bill that was due to take place in the city’s 70-seat Legislative Council would be delayed until further notice.

The legislature is controlled by a pro-Beijing majority.

Many of the protesters defied police calls to retreat and passed provisions, including medical supplies, goggles, water and food among each other.

Some stockpiled bricks broken away from pavements.

The demonstrators rallied just a stone’s throw from the heart of the financial center where glittering skyscrapers house the offices of some of the world’s biggest companies, including HSBC.

HSBC and Standard Chartered, in addition to the Big Four accounting firms, had all agreed to flexible work arrangements for staff on Wednesday, Hong Kong media reported.

Standard Chartered and Bank of East Asia suspended operations at some branches in the area.

The government advised staff to avoid driving to government buildings because roads were blocked as protesters vented their anger and frustration over a proposed law that has generated unusually broad opposition at home and abroad.