The sick children were hospitalized.

Separately, hundreds of children at a primary school developed fever after a mass vaccination.

The killer pneumonia in Qishan County has forced the Yidian Senior High School to suspend classes for one week since last Friday, Xi'an Evening News reported yesterday.

The one fatality was a third-year boy at the school, who died in the provincial capital Xi'an late last week after being treated at several hospitals.

Almost all the sickened students developed fever above 39 degrees Celsius, the report said.

Lu Huming, director of the county's Health Bureau, ruled out severe acute respiratory syndrome (SARS) or bird flu.

The report said provincial authorities were trying to find out what caused the outbreak.

Elsewhere in Xunyang County, 226 children at a primary school sickened after they received measles vaccines. They suffered fever, vomiting and dizziness, local media reports said.

The county's public health agency and the education bureau arranged the vaccination for children between 2-15 years old in the county, according to the local Sanqin Metropolis Newspaper.

However, only children at the downtown Chengguan No. 1 Primary School had the three complaints, the report said. The children were inoculated for measles last Wednesday and Thursday.

The county's disease control and prevention center said on Monday they would investigate.