China seals gas well after leak
Technicians initially ignited the leak to burn as much of the fumes as possible.
CNN's Lisa Rose Weaver on rescuers widening the search area for victims of the gas well blowout.
BEIJING, China (CNN) -- Emergency crews have sealed a natural gas well, capping the source of a toxic gas fumes that killed almost 200 people and poisoned 9,000 others in southwest China.
The disaster – China's worst industrial accident – has left a 25-square kilometer "death zone" around the Chuandongbei well in Chongqing municipality, strewn with bodies in dozens of villages and forcing more than 40,000 people to flee.
The toll from the gas leak stood at least 198 early Saturday, the official Xinhua news agency reported.
Also on Saturday, technicians wearing special breathing gear poured hundreds of cubic meters down the well to plug the gas flow, which has spewed deadly fumes for four days, Xinhua said.
"Cap operation is completed successfully," a Xinhua bulletin said.
The exact cause of the disaster is still being investigated.
According to Xinhua, the gas well "burst" Tuesday in the Chuandongbei gas field, releasing natural gas and sulfurated hydrogen "killing and poisoning many people."
Poisonous gas hovered over the village as many residents slept, making "an area of 25 square kilometers (10 square miles) a death zone," the state-run China Daily reported.
The first casualties were workers from PetroChina, which owns the gas field, a company spokesman told CNN.
"This kind of blowout is not unusual during oil or gas drilling," the spokesman said from the company's headquarters in Beijing.
"It was the sulfurated hydrogen that made this accident so fatal."
Senior executives from the company were on the scene assisting rescue efforts.
Children in hospital had their eyes sealed shut by the gas.
Gas field workers Wednesday partially contained the leaking gas by igniting it and burning off poisonous fumes.
China has a notoriously poor work safety record.
More than 120,000 people died in work-related accidents from January to November this year, the official China Daily said earlier this month.
In its annual safety report for 2002, PetroChina said the company suffered 179 accidents with 38 deaths, including a hydrogen sulfide toxic accident that killed five people.
Chongqing and the neighboring province of Sichuan are among China's major natural gas producing areas.
-- From CNN's Lisa Rose Weaver and Steven Jiang