At least 14 people were arrested in Hong Kong’s Prince Edward neighbourhood on Monday night as hundreds brought flower tributes to mark the one-year anniversary of its railway station being stormed by police.

The gathering came less than 24 hours after a man many believed disappeared that chaotic evening revealed he was not missing at all, but had fled to Britain to avoid criminal charges.

The controversial August 31, 2019, police operation saw riot officers in pursuit of anti-government protesters enter train carriages and beat people with batons and pepper spray. The evening would later generate unsubstantiated claims of deaths that have been repeatedly denied – and denounced – by police and government officials.

While the Prince Edward memorial was at one point an almost monthly occurrence, Monday’s one-year anniversary faced considerably more restrictions, as it was the first time it had been attempted since Hong Kong’s sweeping new national security law was put in place on June 30.

The event was called off last month due to the Covid-19 pandemic, which police cited on Monday in dispersing protesters for violating the citywide ban on social gatherings of more than two people.

Those detained, nine men and five women, aged between 16 and 60, were arrested for offences including unlawful assembly, disorder in a public place and assaulting a police officer.

Among them was a 17-year-old boy said to be impersonating a journalist.

Another 37 people were given tickets for breaching the coronavirus-related measures.

More than 500 police officers were deployed to the scene, raising warning flags and using pepper spray more than once. They took away a 10-year-old boy at one point, noticing he was walking the streets without the company of an adult, but later released him to his parents at a police station.

A pregnant woman reportedly fell during the police dispersal operation and was taken to hospital in an ambulance.

Later, in a statement on Facebook, police said officers pulled away a woman while trying to arrest a man beside her and subsequently used pepper spray. But it came to their attention that she was pregnant and feeling unwell. An ambulance was called, and she was taken to Kwong Wah Hospital in Yau Ma Tei for treatment.

“Police are highly concerned about the pregnant woman being affected during the chaos at the protest and send her our regards,” the statement said, adding the force had sent staff to accompany her and her family.

District councillors for the area said they had received a record high number of white flowers from protesters, even as police officers threatened to fine those who left bouquets on the ground outside Prince Edward MTR station.

The night before, Wong Mau-chun, known by some as “Prince Edward Hon Bo-sun”, released a video, claiming to be one of the men rumoured to have disappeared at the railway station a year ago amid the chaos.

While the man seen pinned to the ground by police was wearing a black mask that covered the lower part of his face during his arrest, his visible features appeared to match those of Wong, who also provided documentation of the charges he was facing.

In the video posted to Facebook on Sunday evening, Wong said he had been laying low because police had charged him with eight offences, including rioting, which carries a penalty of up to 10 years in prison.

While aware many were worried about his well-being during the past months, he said he had not come forward because police had collected his DNA samples and his case was already in the judicial process.

“I would only be helping police if I made clarifications at the time,” Wong said, adding he decided to flee because he was not confident he would receive a fair trial.

A police spokesman said officers have made 69 arrests related to the August 31, 2019, incident, with seven charged with offences ranging from rioting to possessing offensive weapons.

Among those charged, two, including Wong, had absconded, the spokesman said, adding that there were warrants out for their arrests.

Ahead of the anniversary, Hong Kong Commissioner of Police Chris Tang Ping-keung warned on Sunday that those spreading rumours – including the suggestion that protesters had been killed during the episode – could be deemed in violation of the city’s sweeping new national security law.

“For quite some time in the past, some people really wanted to endanger the safety of our country or Hong Kong by inciting many others to do something that they would not normally do or spreading wrong thoughts, or spreading the rumours that someone died on August 31,” Tang said in a television interview.

He refrained from speculating about who was behind the rumours, but said they were desperately hoping to harm the safety of both mainland China and Hong Kong.

In a separate interview with Chinese state news agency Xinhua, Tang said the new security law had achieved a strong deterrent effect, eradicating almost all unlawful assemblies and events involving violence, and noted that more than 20 people had been arrested under it.

“Some have declared they would ‘sever ties’ with violence, while others have fled secretly,” he said, describing how the law had “left those who oppose China and stir chaos in Hong Kong in a state of mayhem”.

His warning to protesters was in line with an earlier one from deputy director Zhang Xiaoming of the cabinet-level Hong Kong and Macau Affairs Office, who on July 1 said those contributing to the rumour mill could run afoul of the security law, because they instilled hatred against police.

But the law did little to deter people like Yip, a nurse, who was only willing to give her first name.

She said she had not frequently attended the previous monthly events, but was driven by what she saw as an increasing clampdown by authorities to show up on Monday.

“We cannot forget the truth,” Yip said, referring to news footage she saw depicting the incident on TV.

Last August 31, riot police stormed into Prince Edward MTR Station to make arrests after receiving reports there were radical protesters inside.

Footage of police officers hitting people in train carriages with batons circulated widely online. That, combined with the denial of immediate access to the station by journalists and later revisions to official injury figures, gave rise to speculation from anti-government critics and protesters that some had died during the operation.

The authorities have repeatedly denied the accusation, and there has been no evidence to support the rumours.

Shortly after noon, a handful of protesters began to turn up at the railway station to chant slogans and lay flowers in a makeshift memorial.

The small group was quickly dispersed by police officers and railway employees, with some given prosecuting summonses for allegedly breaching railway by-laws or littering in public.

A group of Yau Tsim Mong district councillors arrived later, taking flowers from those who came and putting them in a box.

Andy Yu Tak-po, one of the councillors, said that a year on, none of critics’ calls for greater transparency about the event have been addressed, including making publicly available closed circuit television footage from that evening.

“There has been no reflection from the authorities at all,” he said, also accusing the MTR, Hong Kong’s train operator, for not being upfront.

Speaking on the radio, Education University student Kex Leung Yiu-ting urged people to refocus their scrutiny on possible use of excessive force by police during the incident, rather than concentrating on unsubstantiated speculation about deaths.

The student was caught up in the incident last year and subsequently filed a successful court challenge to obtain video footage to pursue a claim against the force.

As the evening wore on, a crowd gathered at the junction of Prince Edward West and Nathan Road, with tensions flaring at times as protesters engaged in verbal disputes with the police trying to disperse them.

Officers raised blue flags, warning protesters of unlawful assemblies, and purple flags, indicating a possible breach of the national security law, during a few of the flare-ups.

They also warned the crowd they could face fixed fines of HK$2,000 for violating the city’s social-distancing regulations, as they pushed the crowd in the direction of Mong Kok, where the crowd eventually broke up.

Separately, a group of students from the University of Hong Kong held a commemoration in Central on Monday in remembrance of Liberation Day, which marked Britain resuming control of its former colony from Japan in 1945 following the end of World War II.