Two students died and more than 20 were injured Wednesday in a primary school stampede in the central Chinese province of Henan, Xinhua news agency reported.

The stampede occurred around 8:30 am (0030 GMT) during a bathroom break at the Number 3 experimental primary school in Puyang County, Xinhua said.

The Puyang county government in Henan province said in a brief notice that the incident is under investigation. A county official reach by phone confirmed the death and injuries but declined to give other details.

Overcrowding and poor building design and construction have been blamed for past crushing deaths and injuries at Chinese schools. Other safety problems have included the use of running tracks made from scrap that sickened students with their noxious fumes.

China deadliest stampede incident in recent years came during New Year festivities on Jan. 1, 2015, when 36 people died in a crush along Shanghai's riverfront esplanade.