Thousands of people gathered outside the charred remains of a high-rise apartment building in Shanghai

Sunday to mourn the 58 people who died last week in a fire that has triggered public criticism and resulted in a dozen arrests.

Relatives of the victims began arriving at dawn to lay flowers before portraits of the dead at an entrance to the block. By the end of the day, an estimated 10,000 people had come to pay their respects, witnesses said.

The fire swept through the 28-story building last Monday after sparks from welding equipment set alight nylon construction netting and bamboo scaffolding. Officials have blamed unlicensed welders who were fixing insulation material to meet energy-efficiency targets.
Most of the victims died inside their own homes, overcome by smoke, toxic fumes and heat. Another 71 were injured, and an unknown number of people are still unaccounted for.

Local authorities had prepared for the crowds by setting up barricades around the building and deploying dozens of volunteers as well as uniformed and plainclothes police.

'Shanghai Don't Cry: Mourn the Victims of Shanghai's Jiaozhou Road Fire,' said small black-and-white posters being handed out by young people wearing badges that identified them as volunteers.

There were no signs of protests, but many victims' relatives and others have criticized the government for responding too slowly to the fire, and failing to enforce safety standards during construction work in China's wealthiest commercial metropolis.

Criticism has been particularly intense among Chinese Internet users, especially on microblogging sites like Sina Weibo.

Central and local authorities have tried to act fast to quell public anger over the fire, which highlights the lax government oversight and poor work practices that are still rife across China's booming construction industry, despite some improvement in recent years.

The fire has raised particular concern over China's efforts to meet energy-efficiency targets by adding insulation to the outside of buildings, as the welders were doing when the fire broke out. The insulating material is supposed to be treated with fire retardant, but it is still flammable. Local authorities in Beijing, the capital, have ordered a halt to such projects, pending reviews and 'rectification' of any problems.
Luo Lin, head of the State Administration of Work Safety, has blamed the tragedy on unlicensed welders, illegal subcontracting and poor management.

Shanghai authorities have ordered fire and safety inspections throughout the city, while the central government has promised a crackdown on lax safety practices at construction sites and public areas in major cities.

Shanghai police have also detained 12 people in connection with the blaze, including four unlicensed welders, as well as project supervisors and building construction managers, according to the state-run Xinhua news agency.

In another move to appease the public, Shanghai's Communist Party chief Yu Zhengsheng, mayor Han Zheng and other senior officials joined the mourners Sunday, offering white chrysanthemums--a traditional symbol of mourning--and bowing three times before the building.