HANGZHOU - As many as 511 students in east China's Zhejiang Province have been infected with norovirus, a common cause of viral gastroenteritis, after drinking contaminated barrelled water, local authorities said on Thursday.

The students from several schools in Haining City and Haiyan County, including three kindergartens and 10 middle schools, are receiving treatment in local hospitals, according to the municipal government of Jiaxing City, which administers the two places.

The outbreak began on February 11 in Haining and February 13 in Haiyan.

An epidemiological investigation showed that norovirus among all the affected students was triggered by contaminated barreled water with the same brand.

Classes will be suspended for three days.

"Norovirus infection is characterized by vomiting and diarrhea. In general it will be self-cured within three to five days," said Chai Chengliang, a health expert with the provincial disease control and prevention center.

The virus can easily break out in densely-populated areas and is transmitted through the digestive system as well as the respiratory system, he said.