Hong Kong’s anti-corruption watchdog is setting up a task force to investigate if police failed to do their duty when civilians were attacked by a mob with triad connections at Yuen Long on July 21, according to local media.

On Tuesday, merchants on Fung Yau Street North in Yuen Long said officers from the Independent Commission Against Corruption (ICAC) had asked them to provide footage from their surveillance cameras, Radio Television Hong Kong reported.

Local media outlets cited sources saying the ICAC had set up a task force to look into whether any police officers committed misconduct in public office in the incident. The move came after local and international media reports showed police officers failed to carry out their duties properly.

RTHK’s Hong Kong Connection TV program acquired surveillance camera footage from some shops on Fung Yau Street North on the day of the attacks. The footage appears to show several police vehicles going by without taking any action, despite the fact that hundreds of men in white T-shirts, some wielding bamboo sticks, were seen gathering around the area.

The police force has been heavily criticized and accused of failing to prevent the attacks and protecting civilians because of their late response to the attack, even though they had received intelligence beforehand.

The force also faces allegations of collusion with triad organizations in the district. The violent Yuen Long attack not only shocked Hong Kong people, but also the international community, leaving many wondering why the police failed to stop the violence.

On July 21, hundreds of thugs dressed in white T-shirts and armed with iron rods, rattan canes and wooden sticks stormed into Yung Long MTR Station and attacked people dressed in black – the dress code for the anti-extradition bill protesters.

The thugs indiscriminately attacked protesters, Yuen Long residents on their way home, journalists and commuters in the concourse, platform and even inside the train carriages. A total of 45 people were injured and sent to hospital.

The police were heavily criticized as they reached the station 39 minutes after the attack, despite numerous calls to emergency hotlines and the fact they had received intelligence the day before about the attack.

One video clip posted online showed two police officers arriving at the station 12 minutes after police received calls, but they left without taking any action while the white-clad mob was still gathering inside the station.

More footage showed the white-clad mob gathered in Nam Pin Wai village near the station, brandishing what appeared to be metals rods, but riot police stood nearby and did nothing. No one was arrested that night.

In the following days, police arrested a total of 12 people for alleged unlawful assembly. Some of those arrested were said to be triad members.

Read: Hong Kong rocked by armed mob attacks

Although the police force defended its actions due to deployments to handle another protest in Western District on Hong Kong Island on the same day, Anthony Tsang, the acting New Territories North regional commander, admitted last Thursday at a press conference that “there may be some room for improvement in the deployments.”

RTHK’s Hong Kong Connection program in Cantonese with English subtitles.

The New York Times also released a video on Tuesday, saying it had also found footage that appeared to show some policemen failing to carry out their duties.

Legal scholar Eric Cheung Tat-ming of the University of Hong Kong said that judging from the media coverage, there seemed to be a reasonable basis for the ICAC to start an investigation into the police’s action, RTHK reported.

Cheung added that someone can be convicted of misconduct in public office if he or she deliberately refused to conduct his or her duty without a reasonable explanation.

Barrister Stephen Char Shik-ngor, who had once served as a chief ICAC investigator, cited an English case from 1979 which saw a British police officer get convicted for the offense of standing by and watching a person die of assault, the Hong Kong Economic Journal reported.

Char said it was unacceptable that the two officers who did arrive at the scene soon after receiving a call then left without trying to stop the attacks.

In an early press briefing, the police management said the two officers left because they were afraid they would get hurt, so they decided to leave and wait for backup.