No one had ever seen the men in the white gloves before.
The workers at a Beijing construction site had been told they would be paid that day, after months of waiting. Instead, a bus rolled up and several men poured out and slipped on white gloves, two witnesses say. Then the gloved newcomers descended on the migrant labourers outside their dorm, punching and kicking some of the men.
Captured on video, a man in an orange construction helmet shoves one man into a wall, while another in a red coat kicks that same worker in the stomach, sending him aloft. A man holding a stick stomps another worker curled on the ground, as others in white gloves join in. The clip ends when one of the gloved men confronts the person holding the camera.
One victim that day suffered three broken ribs and the other a fractured cheekbone, one witness says. The police were called but no one was arrested.
The unspoken message delivered to the workers at the state-run construction site was that they should accept any pay, even if not the agreed amount. In fact, the workers received tens of yuan a day less than promised, two witnesses say. And the crew became part of the growing cycle of violence inflicted on undocumented labourers at mainland construction sites.
"Violence is getting more and more serious. It is definitely common," says Li Dajun, from the non-government organisation Beijing Practitioner Cultural Development and Research Centre for Migrant Workers.
The muscles of 40 million migrant workers have built cities and fuelled the development and construction industry worth about 12 trillion yuan (HK$15.2 trillion), according to 2012 government statistics.
But the same workers routinely endure physical attacks, lost or unpaid wages and poor workplace protections, says Pun Ngai, a sociology professor at Hong Kong Polytechnic University who researches migrant workers.
Construction work is considered one of the riskiest fields for migrant labourers, who - because they are not documented when they move from their small towns to find work - are rarely covered for workplace injury, missing wages and abuse because of developers' close ties with the state, Pun explained.
There is little incentive for local governments to enforce labour protection policies, she says, given local connections to construction companies.
As a result, a highly exploitative and corrupt labour system thrives. "The construction industry exists above the law," Pun says.
The mainland's labour laws have failed to keep violence and exploitation at bay within the construction industry. Pun says there is little incentive for local government to seriously implement the labour protection policies, given their connections with construction companies and vested interests.
Multiple tiers of illegal and corrupt subcontracting has led to the money not reaching the workers who actually do the physical work, as thugs are hired to force workers to submit to lower wages, Li says.
The workers captured in the video were assigned to a construction site belonging to China Construction First Building Corporation Limited - a subsidiary of the publicly listed China State Construction Engineering Corporation Limited, whose mother company is state-owned China State Construction Engineering Corporation.
Calls to the police and the China Construction First were not returned. A employee of the China State Corporation said the problem was unrelated to its work and directed inquiries to First Building.
The thugs who delivered the beatings in the video were hired by a labour recruitment company employed by the developer, a worker says. It's common to force workers to accept wages lower than previously agreed upon, according to the Beijing migrant workers centre. "I thought that because the construction company was a big and reputable one and the labour recruitment company they hired was also a big one, it'd be some sort of a protection guarantee," says one worker who was employed at the First Building site.
[Names of the workers, recruitment companies and the construction sites have been withheld to protect construction workers who fear retribution.]
Each year before Lunar New Year, migrant workers and the frontline subcontractors wait nervously to see if wages will be paid. Pun says it is during this period that most violence occurs.
The 2008 labour contract law requires companies to sign contracts with workers, to contribute to their welfare accounts and pay their standard wages every month. But the law is often flouted, Li says.
"Documents proving labour relations are with the management - the company. The frontline migrant workers don't get to read the documents, let alone set the terms. The labour relationship is covered and hidden," Pun says. "In most cases, there isn't even a contract, just a verbal agreement.
"If there was a contract, it's usually an empty shell where wages will be the lowest possible wage, written in case government officials check."
Construction companies rely on subcontractors that hire labour recruitment companies who in turn further subcontract the work. It could take six to seven subcontracting levels before finally finding the person who directly hired workers, Li says.
"Each level will skim some money, so when it trickles down to the lowest level, the frontline workers get nothing," Li says.
To control dissatisfaction, companies sometimes hire triads to keep workers in line.
"When companies hire triads to beat up workers, they see it as maintaining order," Li says. "There has never been a management company employee nor triad member punished by law.
"So if you fight for these workers' rightful wages and for labour contracts, you're actually challenging the whole food chain and the whole system. They will fight you together."
Workers don't feel it's within their right to protest, Li says.
When the thugs starting beating workers at the Beijing site, 50 workers stood by watching. "None of them dared to help," Li says.
"The most important thing is to give migrant workers the freedom to form bodies - unions - to be their voice. But currently unions in China are there to protect the state and the establishment."
Violence broke out at another site in January after a company failed to pay wages on time. Labourers begged the local government and police for help. Thugs soon arrived at the worksite run by China Construction Eighth Engineering Division Corporation Limited, another subsidiary of China State Construction.
Some workers were beaten, some jailed for a day, while others had their belongings ransacked. Later some workers there got partial wages ranging from 100 yuan to 200 yuan a day despite being promised 280 yuan.
"I was one of the last two to receive my wages. But then thugs beat me up again and took my wages, with the government and the company officials watching," one worker recalls. "Officials just said: 'you can't beat him in here'."
They directed the attackers to take him outside.
Some workers never received their wages.
China Construction did not respond to a reporter's queries.
Despite the abuse, every worker interviewed says he would be returning to a construction site.
"We'll all go back," one worker says, "once there's a job."