NANNING - Twenty-seven pupils were injured, including four in serious condition, after falling from a two-storey teaching building in South China's Guangxi Zhuang autonomous region Thursday, local authorities said.

A policeman installs security tape around a primary school building in Liujiang county, South China's Guangxi Zhuang autonomous region, Oct 21, 2010. A total of 27 pupils were injured, four seriously, after falling down from the second floor of the two-story school building after a guardrail collapsed at 4:40 pm on Thursday. [Photo/Xinhua]

The accident occurred at about 4:40 pm after the collapse of the porch guardrail on the second floor at Luoman Central Primary School in Liujiang county of Liuzhou city, the county's publicity department said in a statement.

All the injured are being treated at hospitals in Liujiang and Liuzhou, it said.

The guardrail collapsed after being crushed by dozens of students who rushed to the second-floor of the 31-year-old building to return sports equipment after a physical education class, the last class of the day.

A total of 27 students lost control and fell from the second floor, the department said.

The building has been listed as a level 2 dangerous building in a 4-level category, but it can still be used according to regulations, it said. Level 4 is the most dangerous.