Hundreds of thousands of protesters on Sunday joined a rally and march in Hong Kong as part of a weeks-long show of civil unrest against a controversial law and police use of force.

"Free Hong Kong! Democracy Now!" "Withdraw the bill! Investigate police brutality!" a massive crowd chanted at a rally in Victoria Park on Hong Kong Island that was approved by police.

Jimmy Sham of the Civil Human Rights Front, which organized the rally, told those gathered at the park that Chief Executive Carrie Lam's administration has neglected protestors' demands.

"She must respond to peaceful, rational and non-violent protest," he said. "We have witnessed enough of humiliation of the people by Hong Kong police. Supervision must be put in place to curb police violence."

Apart from full withdrawal of a now-suspended bill that would have allowed fugitive transfers to mainland China, protesters also want an independent probe into alleged police brutality, pardons for arrested protesters, and democratic political reform.

As waves of people continued to pour into the park, thousands began spilling out onto nearby streets in the afternoon. They marched westward towards the central business district in defiance of police, which had banned the march citing security reasons.

Some subway services skipped nearby stations for hours as part of crowd control measures. Bus services were also suspended as marchers filled the roads nearby.

As rain started to fall, roads from Causeway Bay to Central turned into a colorful sea of umbrellas held by protesters.

They continued marching into the night, though in relatively smaller numbers.

"The government has so far failed to answer to the people," said Anne Tsang, a 45-year-old medical equipment supplier. "As long as the bill is not withdrawn, any response the government makes is fake and only meant to deceive. We will not back down."

Tsang said setting up an independent inquiry into police use of force would be a welcome sign that the government is willing to listen. "I am most upset that young protesters are being beaten. We all have a duty to stand up speak out," she said.

Some protestors wore eye patches in a show of solidarity with a woman recently shot in the eye by police with what was believed to be a bean bag round. Many decried injuries suffered by protestors in police custody.

The police have denied the allegations, in particular of a strip search of a woman by male officers.

So far, about 750 people have been arrested for offenses including rioting, unlawful assembly, assaulting police, possessing weapons and obstructing police in the performance of their duty, according to the police.

The government has said in a statement it regrets that the demonstration targeted police. "The police have been handling these illegal acts with tolerance," the statement said.

Two water cannon vehicles were on standby, local media reported.

In Shenzhen City across the mainland border, the People's Armed Police Force, a paramilitary force, and armored vehicles were seen gathering in recent days at a stadium. According to some reports they could be preparing to enter Hong Kong to assist in restoring order should police fail.

Former Secretary for Justice Elsie Leung said in a radio program Sunday that the current situation is "near subversion" but not yet affecting national security and does not warrant declaring a state of emergency.

Millions of people have taken to the streets since June in protest against the extradition bill.

Government leader Carrie Lam suspended the bill's legislative process and later declared it "dead" in a bid to quell public anger. But the bill has not actually been withdrawn, and the protests continue to draw large crowds.

Some of the protests have turned violent and resulted in clashes between police and protesters, with officers resorting to tear gas, rubber bullets and other tactics, and crowds countering by throwing bricks, bamboo sticks and gasoline bombs.