Police in Dongyuan county, Guangdong, have detained four suspects, including a security guard, in connection with the brutal attack on dozens of migrant workers striking over unpaid salaries. At least one worker was killed and more than a dozen others were wounded - six of them seriously - after they tried to confront the management of Fuyuan Energy, the contractor for a Dongyuan county hydroelectric power station, said Qiu Xiaowei, a spokesman for a Fuyuan Energy subcontractor. The ferocious attack has once again underscored the plight of migrant workers on the mainland, who are vulnerable to labour abuses due to a lack of workplace protection. Xinhua said the workers were hired by Qiutian Construction and the two companies had failed to agree on a compensation deal after the site was flooded last year, causing the subcontractor substantial losses. Mr Qiu agreed the workers should have been paid on time even though the two companies could not come to financial terms, but said 'we have left no money to pay them because we haven't seen any money from Fuyuan for four months'. He added that Fuyuan Energy owed his firm about 30 million yuan. Fuyuan Energy and its parent company, the Shenzhen-based Fuyuan Group - owned by Miao Shouliang , a member of the Chinese People's Political Consultative Conference - refused to comment. Xinhua said the fight erupted after some of migrant workers hired by the subcontractor began removing equipment from the site on Friday. But Qiutian Construction denied the allegation and Mr Qiu said the workers were simply there to demand back pay. Armed with shovels, axes, iron clubs and knives, security guards and more than 300 thugs hired by Fuyuan Energy attacked the workers. One worker told the Chongqing Morning Post that his leg had been broken. Xinhua reported that the various levels of government in Dongyuan had set up a special task force to look into the labour dispute. Construction Minister Wang Guangtao is reported to have ordered a probe into the beatings. However, Mr Qiu accused the city government of not doing enough because of Fuyuan Energy's high-profile owner, and said 'even the local media has been silent. We're left alone to look after the victims.'