( CNN ) -- A stampede at an elementary school in central China killed four students and injured more than 10 others Wednesday morning , authorities said . The cause of the crush at Qinji Elementary School in Hubei province is still under investigation , the state-run news agency Xinhua said in a short report . State-run broadcaster CCTV reported that it happened after an iron gate at the students ' dormitory failed to open . As the children were unable to exit through the gate , a large number of people built up against it , CCTV said . The pressure caused the gate to collapse , resulting in the stampede , the broadcaster reported . It was n't immediately clear why the gate would n't open . A photograph carried by Xinhua showed one of the students injured in the crush , Zhang Jiali , receiving treatment on a bed in a hospital in Laohekou City in Hubei . The child was still dressed in a purple jacket and stripy , wooly leggings . A total of 11 children were injured in the stampede , authorities in Laohekou said on their microblog account . A number of stampedes have taken place at Chinese schools in recent years . In 2009 , eight students were killed and 26 were injured in an incident at a middle school in Hunan province . And in 2006 , a stampede was reportedly set off in a middle school in Sichuan province by a student who stopped to tie shoelaces on a staircase . The resulting crush killed eight people and injured 27 . CNN 's CY Xu in Beijing and Tim Schwarz in Hong Kong contributed to this report .
NEW : The crush was caused by a gate that would n't open , state media report . NEW : Eleven students are injured in the stampede , local authorities say . It took place at an elementary school in Hubei province .