Cleanup crews in northern China were scrambling Thursday to absorb 60 tons of toxic coal tar accidentally dumped into a river before it reaches a reservoir serving 10 million people, state media said.

The incident occurred Monday when a truck carrying the coal tar fell into the Dasha river in Shanxi province, the official Xinhua News Agency reported.

Cotton batting, sponge, straw and activated carbon were being used to try to absorb the coal tar — a substance linked to cancer — before it reaches the Wangkuai Reservoir of Baoding, a city of about 10 million, Xinhua said.

Some 24 dams also were set up along the Dasha river to slow the pollution's flow downstream, Xinhua said.

By Tuesday, the pollution had reached Hebei's Fuping county, where some 50,000 residents rely on the river for drinking water, Xinhua said. The agency said Fuping residents were told to take water from nearby reservoirs and seven standby wells until the river could be cleaned.

Baoding, in neighboring Hebei province, is about 45 miles from the site of the accident, Xinhua said. The report said the pollution was traveling downstream at less than 1 mph.

Baoding city officials were preparing for the pollution to reach the reservoir but did not know when it would arrive, said a man who answered the phone at the Baoding City Environmental Protection Bureau. He would only give his surname, Qin.

Qin said the Wangkuai was not used for drinking water but for irrigation and industrial use. He said a second city reservoir, the Xidanyang, was a dedicated drinking water source.

There have been no reports of people being sickened by the contaminated water, Xinhua said.

Xinhua said the truck carrying the coal tar was heavily overloaded when it crashed, and the driver did not tell traffic authorities he had been carrying the load when he reported the accident, delaying cleanup efforts. The driver, whose name was not given, has been detained by police.

The report did not say when the cleanup began. There have been no reports of people being sickened by the contaminated water, it said.

Prolonged exposure to coal tar has been linked to increased rates of certain cancers, but it also is used in small doses as a topical medicine to treat eczema and other skin diseases, according to the World Health Organization's International Agency for Research on Cancer.

China's State Environmental Protection Bureau in Beijing referred calls to the local Shanxi Environmental Protection Bureau, where a man who answered the phone confirmed that the spill had occurred but would not give additional details. He refused to give his name.

Most of China's canals, rivers and lakes are severely tainted by industrial, agricultural and household pollution.

Since a major chemical spill on the Songhua river in northern China in November halted water supplies to tens of millions in China and Russia, there have been at least 76 more water pollution accidents, the government said.

In the Songhua incident, local authorities were accused of reacting too slowly and delaying public disclosure.