Workers at a construction site in Luwan district of Shanghaiare learning how to use fire extinguishers, Nov 19, 2010. All construction sites in the municipality stopped work for two hours on Friday morning to check for fire hazards. [Photo/Xinhua]

SHANGHAI - Local police have detained four more people on suspicion of involvement in the fire that gutted a high-rise apartment building in downtown Shanghai on Monday, as the death toll rose to 58, authorities said on Friday.

This has taken to 12 the number of people held on suspicion of being responsible for the blaze.

Related readings:  Donations pour in for Shanghai blaze victims  Shanghai blaze is a warning  Remembering Shanghai's fire victims  China orders fire-safety overhauls after Shanghai blaze  Shanghai fire completely avoidable: official

Eight people were already taken into custody on Tuesday, including four unlicensed welders who were working on the building's energy efficiency improvement project when the fire started, and corporate executives from Jiayi Building Decoration, the construction company.

The four latest detainees were corporate representatives from the project contractor Jing'an Construction, parent company of Jiayi, from Shanghai Jing'an Construction Supervision, the firm hired to oversee the quality of the project, and from the property management company.

Meanwhile, DNA tests have confirmed five more fatalities from the blaze, taking the death toll to 58, according to a brief statement on the municipal government's website on Friday.

The 58 dead comprised 22 men and 36 women, it said.

The inferno also left 16 of the 71 people hospitalized in critical condition and dozens more were still missing.

A 3-year-old boy who has recovered from his injuries is likely soon to become the first victim to be discharged from hospital, said the municipal health bureau.

Unlicensed welders working on energy efficiency improvement projects were blamed for starting the fire, one of the worst in Shanghai's history, when sparks from their welding ignited the nylon nets and bamboo scaffolding shrouding the building.

Investigations also showed that other illegal practices, such as multi-layered subcontracting and lax supervision, led to the disaster. The government has therefore ordered a citywide inspection into the safety of construction sites.

Many people also blamed the inefficiency of firefighters, who took four hours to put out the fire.

"I saw them demonstrating so much efficiency while in drills on TV, but this time it just took too much time," said one resident surnamed Shi.

The charred building, and another two nearby, were undergoing government-led energy efficiency improvement projects when the fire broke out.

Officials in the Jing'an district, where the fire occurred, said that the work to improve the energy efficiency of the other two buildings would continue despite the fire, according to an Oriental Morning Post report.

A new plan for the renovation project would be unveiled soon, with safety measures highlighted and prioritized, said the report.

The plan would also need the approval of residents before it starts, it said.

But one resident surnamed Wang said that he would rather not have the buildings renovated.

Wang and his neighbors from the adjacent two buildings were evacuated after the fire started and relocated in nearby hotels.

"My confidence in the quality of the renovation project has been greatly dented. I only want to get back home as soon as possible," he said.

Victims of the fire and their relatives have also been accommodated in nearby hotels, with doctors available 24 hours a day to provide trauma counseling.

"Many victims who escaped from the fire woke up in the night from nightmares about it, and I saw doctors come to their aid," said one security guard at Jiuyue Hotel, which is located 100 meters from the scene of the fire.

Wang Hongyi contributed to this story.