Wei Jingru, 7, is treated at a hospital in Guangshan county, Henan province, on Saturday. Wei was one of 22 schoolchildren injured in an attack at a local primary school on Friday morning by a man carrying a knife. WANG ZHONGJU / FOR CHINA DAILY

The man who attacked primary school students with a knife on Friday began the assaults without uttering a word.

That's what Zhang Xiaowei, a student at the Chenpeng Village Primary School, told Southern Metropolis Daily about the rampage that sent 22 of his classmates and an elderly woman to hospitals. Police later detained Min Yingjun, 36, a resident of Chenpeng village, Wenshu township in Guangshan county, on suspicion of being the attacker.

Zhang said the man he saw burst into his classroom had wild hair and was wearing blue long underwear without pants and no coat. It "seemed like he had mental problems", the boy was quoted as saying.

In other classrooms, students prevented the man from breaking in by using their bodies to barricade the doors.

The primary school, which has more than 300 students, had no one standing guard at its gates. Anyone was free to go in and out, according to Chinese media reports.

Earlier on Friday, Min is believed to have broken into the house of Xiang Jiaying, an 85-year-old woman, and wounded her with a knife he stole from her kitchen before the attack at the school.

The police managed to seize the suspect with the help of village officials outside the school.

Min is believed to be mentally ill and to have epilepsy.

His father, Min Zheng'an, told West China City Daily his son has had epilepsy since 1991 and that the symptoms of his condition had become more serious since April, media reports said.

The police arrived at Min Yingjun's home on Friday evening and left with his medical records and medication, his father said.

Zhang Zhixun, a resident in Min's village, said the suspect used to have about four seizures a day.

"When he was having a seizure, he would always twitch on the ground, foam at the mouth and his lips would turn purple, which was caused by him not having enough oxygen," Zhang told China Daily on Sunday.

Min has a 2-year-old daughter and a 10-year-old daughter. His wife is a migrant worker in the city. The motive of the attack remains unclear.

Most of the students and the woman who were injured received head wounds, and at least seven seriously injured students were transferred to hospitals in Wuhan, Hubei province, and Xinyang, Henan province, on Friday afternoon.

Police took Min to the county hospital, where he was diagnosed as having mental troubles, a doctor told West China City Daily.

Since it released a press statement about the attack on Friday, the local government has remained silent.

China Daily phone calls to the publicity department and the head of the education bureau of the county government went unanswered on Sunday.

This was not the first time violence has broken out at one of the county's schools.

Liu Peng, 17, a student at Guangshan No 2 High School, was killed by a classmate with a knife during a physical education class in October 2011. And Cheng Qian, 18, a student at Guangshan No 1 High School, was stabbed to death in front of the school's gate last month, according to Xinhua.

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