Seven children are dead and a dozen more are injured after a deadly knife attack in China, according to the New York Times. The attack took place in the Shaanxi province southwest of Beijing.

The attack took place around 6 p.m. local time outside a middle school where the suspect reportedly graduated from many years before. Police apprehended the alleged knife-wielder, a 28-year-old man who the Times said was seeking revenge for bad experiences he had at the school.

The suspect told police that he was bullied at the school and resented it, according to USA Today. Two boys and five girls were among the dead, while three boys and nine girls were injured and are being treated at a hospital.

China Global Television Network tweeted out video of the crime scene and the man being detained.

News reports attributed the attack to a combination of two factors. One, since China has strict gun control laws, knives are the preferred weapon in mass attacks like this. There have been several such knife attacks in the populous country in recent years, per USA Today.

In January 2017, for example, 11 kindergarten students were wounded by a man with a kitchen knife. Schools have increased security with cameras and gates in the aftermath of such attacks, according to the Times.

The other major factor is an apparent lack of sufficient mental health care in the country of almost 1.4 billion people.

knife attac A knife attack killed seven children outside a Chinese middle school. Pictured above are police outside the site of a previous Chinese knife attack in Beijing. Photo: Jason Lee/Reuters