NANZHENG, China, (Reuters) – Seven children and the  owners of a kindergarten were hacked to death in northwest  China yesterday, the latest in a string of assaults on  schools, prompting officials to vow to “strike hard” to calm  public alarm.

Eleven children were wounded in the attack soon after the  school day started in Nanzheng county, a rural corner of  Shaanxi province, the official Xinhua news agency reported.

Two children were in serious condition.

A 48-year-old man, Wu Huanming, used a kitchen cleaver to  kill five boys and two girls as well as the mother-son team who  owned and ran the private kindergarten, Xinhua said.

Wu then returned home and committed suicide, Xinhua said,  citing a statement from the province emergency office. “His  motive for the attack was not immediately known,” it said.

One local man, Zheng Xiulan, said the attacker had rented  out the rooms for the privately run kindergarten, located in a  row of low houses with concrete yards.