HONG KONG (AP) — A massive rally Saturday in downtown Hong Kong to commemorate the fifth anniversary of the city's 2014 protest movement ended early after violence broke out, with police firing tear gas and a water cannon after protesters threw bricks and Molotov cocktails at government buildings.

Police said in a statement that "radical protesters" lobbed gasoline bombs while some damaged property outside the government offices and aimed laser beams at a helicopter, posing "a serious threat to the safety of everyone" in the area.

The violence was a familiar scene that has been repeated since the protests started in early June in the semiautonomous Chinese territory. It also came three days before a major march is planned on the day China celebrates the 70th anniversary of the Communist Party taking power, sparking fears of more violence.

Organizers said 200,000-300,000 people were at the rally, while police did not immediately give a turnout figure.

More than 1,000 protesters streamed onto a main road, with some targeting government buildings that were barricaded. Police initially used a hose to fire pepper spray after some demonstrators threw bricks. A water cannon truck later fired a blue liquid, used to identify protesters, after protesters lobbed gasoline bombs through the barriers.

Wails of anger could be heard from people leaving the rally when they saw the water cannon. "Damn government," one woman yelled as she hastily left with her daughter.

Many protesters used umbrellas to shield themselves and retreated but returned after that. Scores of riot police poured onto the road and protesters fled into nearby streets.

Police had approved the rally at Tamar Park to commemorate the 2014 Umbrella Movement, in which protesters occupied key thoroughfares in the same area for 79 days beginning Sept. 28, demanding free elections for Hong Kong's leaders.

Security was tight around the government offices and the Legislative Council building, which had been stormed by protesters in July. Exits to several subway stations and many shops were also shuttered.

Demonstrators unfurled a large banner that read "We are back" on a footbridge to the government office. A staircase leading to the bridge was turned into a veritable gallery of protest art, with posters stuck on every available surface of the walkway. One read "Persevere until final victory."

Some protesters trampled on pictures of Chinese President Xi Jinping and Hong Kong leader Carrie Lam that were glued to the floor. At one of the gates to Lam's office, the Chinese word for "hell" and an arrow pointing to the building were spray-painted on the sidewalk.

"We think we will lose because their force is so strong," said one demonstrator, 22-year-old Sang Chan. "But if we don't do anything now, we'll have no other chance."

A 32-year-old protester who would give only his surname, Chau, said they hope to wear down the government. "It's like a marathon to see who gets tired first," he said.

In a statement, a government spokesman said universal suffrage is enshrined in Hong Kong's constitution but called for peaceful dialogue. The spokesman said the government would "assess the situation carefully and take forward constitutional development" in accordance with the law.

Activist Joshua Wong, who played a key role as a youth leader in the 2014 protests, which ended without any government concessions, addressed the rally. "We are back with even stronger determination," he said.

Earlier Saturday, Wong, 22, announced plans to contest district council elections in November. He said the vote is crucial to send a message to Beijing that the people are more determined than ever to win the battle for more rights.

Wong, who has been arrested and jailed repeatedly, said he is aware he could be disqualified but warned it would just generate more support for the protest movement. Members of the Demosisto party that he co-founded in 2016 have in the past been disqualified from serving and running for office because they advocated self-determination.

Wong is out on bail after he was rearrested with several other people last month and charged with organizing an illegal rally. It didn't stop him from going to the U.S., Germany and Taiwan to drum up support for the current protest movement, which started over an extradition bill but has since snowballed into an anti-China campaign.

The now-shelved bill, which would have sent some criminal suspects for trial in mainland China, is seen as a jarring example of China's intrusion into the city's autonomy.

More protests are being planned, including a major march Tuesday that has sparked fears of a bloody showdown that could embarrass China's ruling Communist Party as it marks its 70th year in power with grand festivities in Beijing. Pro-Beijing groups have also vowed to come out.

Police have banned the march, but in the past that has not stopped protesters from showing up anyway. Hong Kong's government has toned down National Day celebrations, canceling an annual firework display and moving a reception indoors.

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Associated Press writer John Leicester contributed to this report.