After failing to put out the fire, the four workers fled without warning others, police say.
Police have detained at least 12 people in a deadly Christmas fire in central China, among them four welders whose apparently careless work started the blaze that killed 309 people, state-run media reported Thursday.
Police allege the four were welding steel beams in the basement of a shopping plaza in Luoyang city Monday night when sparks fell on wooden furniture, the reports said. When they were unable to extinguish the flames with water, the men reportedly fled without warning others.
The flames only reached the first-floor lobby, state news agency Xinhua reported, but the smoke rushed quickly up stairwells, suffocating trapped partygoers in a disco on the fourth floor, where most of the people died.
Among the detained were six managers and employees of Dennis Co., a Taiwan-funded supermarket chain that ran the Dongdu Commercial Building where the fire took place, the Luoyang Evening News quoted the deputy head of public security in Henan province, Liu Guoqing, as saying.
The identities of other people detained were not immediately clear. All were taken into custody Wednesday afternoon.
President Jiang Zemin expressed "extreme concern" with the accident and called for a speedy investigation, Xinhua reported. He ordered local officials to "do a good job in dealing with the aftermath of the fire."
Officials throughout China were ordered by the Public Security Ministry to shut down unlicensed and unsafe dance halls and to check hotels, shopping malls and other public venues.
In Luoyang, relatives tearfully scanned the lists of victims as reports emerged of years of safety violations at the Dongdu Commercial Building. The shopping center was declared unsafe three years ago but never made fire safety improvements, Xinhua reported.
The fourth-floor disco had no emergency exits, Xinhua said, and of the two regular exits, one was filled with smoke and the other hidden from view behind a bar, survivors quoted on the Web sites of local newspapers said. Smoke also prevented firefighters from getting inside, and panicked patrons were hanging out windows and balconies hoping for rescue.
Wang Weihong, a survivor quoted by the Southern Daily newspaper, said she and her boyfriend escaped by smashing the window in a private back room of the disco and were rescued by firefighters at 1 a.m., half an hour after the fire was put out. Three others in the room succumbed to the smoke and died, the newspaper reported.
Other victims included construction workers doing renovations elsewhere in the building. Construction workers in China often labor around the clock, and at least 100 were at work when the fire occurred, the Southern Daily reported.
Authorities have turned up a history of delinquent management at the building, particularly over fire standards. Provincial inspectors listed the building, leased to private managers, as one of the 40 most dangerous commercial outlets in Henan province in 1997, Xinhua said.
Luoyang authorities pulled the building's license to lease recreational space, but managers continued to rent the fourth floor as a disco, the report said. Shop space was leased to private businesses without legal contracts, it said.
The managers recently signed a contract with a Taiwanese investor to make renovations, Xinhua said, and work was under way when the fire broke out.
Officials stood by the death toll of 309, but other news reports suggested it could be higher. The Southern Daily newspaper reported that some 600 people were in the shopping center at the time of the fire, 500 of them in the disco, based on ticket sales.
On Wednesday, scores of people filed into a makeshift government office in the downtown Luoyang Hotel for word on family members feared dead. Bodies were being kept at a morgue elsewhere in Luoyang, an ancient city located along the Yellow River.