Six gas workers have gone on trial in China over a well explosion in December 2003 which killed 243 people.
Nearly 10,000 people were injured by the gas leak
Some 9,000 people had to be treated after the blast near Chongqing city, which spewed toxic fumes over several mountain villages.
Investigators blamed the blow-out on a drilling crew's negligence, and the six men are accused of dereliction of duty.
The trial, at a court in Chongqing, is expected to last for three days, according to Xinhua news agency.
The defendants range in position from former chief engineer to drill operator at the Chuandongbei gas field, according to Xinhua.
Some 60,000 villagers were forced to flee the area around the gas field after the explosion at a well released natural gas and sulphurated hydrogen.
Many of the dead were children or elderly people who were unable to flee after the explosion.
Survivors suffered gas poisoning and skins burns from exposure to the fumes.
Medical workers who disinfected eight villages close to the site of the leak removed almost 4,000 animal carcasses.
The area was dubbed the "zone of death" by the Chinese media.
Engineers had to pump 480 cubic metres of concrete into the burst gas well in order to seal it.
Many villagers were forced to sleep on floors in schools and government buildings in nearby towns before it was safe for them to return home.