Surveillance video has captured an attack at an elementary school in central China, where a knife-wielding man slashed 22 children, the latest in a series of attacks on schoolchildren in the country. The wounded are being treated at hospitals.

The attack happened on Friday -- the same day 20 children were gunned down in a school massacre in the United States.

The suspect is still at large.

Officials are still trying to understand the motive.

A wave of violence in China has led to calls for more protection for the young -- in a country where many parents have only one child.