Four people directly responsible for 8.7 tons of toxic chemicals leakage into a river in North China's Shanxi Province have been dismissed, local authorities said Sunday.

   Chen Jianwen, Tianji Coal Chemical Industry Group general manager, Ren Yongjie, the group's deputy manager who is in charge of work safety, and two heads of the plant's storage workshop were sacked, Liu Dashan, Shanxi provincial environmental bureau's chief engineer, told the Xinhua News Agency.

    The leak triggered widespread water cutoffs in several neighboring provinces and was concealed by the local government for five days.

"We have reported the accident as procedures dictate," said Wang Yiping, spokesperson of the government of Changzhi, Shanxi Province, "The procedure stipulates that we do not have to report it to the provincial environmental protection department if the contamination is contained within the city's geographical jurisdiction."

However, the regulations in Shanxi state that local governments must report to a higher level of government should a major accident or an accident whose severity can not be immediately determined occur.

The aniline concentration level at Wangjiazhuang water monitoring station on the border of Shanxi and Hebei provinces reached 720 times safe levels before Saturday and dropped to 34 times safe levels by 2 am Sunday morning.

Aniline is a toxic chemical widely used to manufacture pigments, herbicides and other chemicals.

An initial investigation revealed that 8.7 tons of aniline was leaked from a broken pipe owned by the Tianji Coal Chemical Industry Group. The leak was discovered on December 31, 2012 by a plant employee during a routine check, by which time the aniline has already found its way into the nearby Zhuozhang River through a loose drainage valve in the plant.

Liu Dashan, deputy director of the Department of Environmental Protection of Shanxi Province, told the China National Radio that his department was notified of the leak on Saturday, five days after the incident took place.

"We are stunned by the fact that the Changzhi government held the news back from the public for five days," a Handan resident surnamed Lu told the Global Times, "I don't think they considered the consequence that people would drink the toxic water."

Another 30 tons of spilled aniline was contained in a nearby deserted reservoir, according to Xinhua.

Changzhi government said the leak has not resulted in any deaths and the water quality has been improving.  "The local government and the chemical plant have implemented a contingency plan after the accident. Five monitoring stations were set up and the data on water pollution is reported to the local authority every two hours," the government statement read.

Handan in Hebei Province and Anyang in Henan Province, both located on the river's lower reaches, have cut off water supplies.

"We have not found aniline in our tap water but the government decided to cut the water supply from the Zhuozhang River and switch to underground water in case the river was contaminated," a spokesperson surnamed Li from Handan Water Supply Company told the Global Times.