More than 50 people, mostly children, were injured by a man who broke into a kindergarten in south-western China and sprayed them with corrosive liquid, local authorities said Tuesday.

The suspect, a 23-year-old surnamed Kong, entered the kindergarten by climbing a wall before spraying victims with sodium hydroxide, said police authorities in Kaiyuan city, Yunnan province.

Police said Kong had intended to take revenge on society after growing up with divorced parents and then encountering difficulties in work and life.

The attack took place on Monday at 3:35 pm (0735 GMT), Kaiyuan Public Security Bureau said on their Twitter-like Weibo account.

Local reports claimed the violence happened in Kaiyuan Dongcheng Kindergarten.

Some 51 children and three teachers were admitted to hospital for treatment, two with ‘severe symptoms’.

Police arrested Kong less than an hour after the assault.

‘Because his parents divorced during his childhood, the lack of family warmth resulted in psychological distortion,’ said police, adding that Zhang’s work and life were unsatisfactory as well.

All this created a ‘pessimistic mentality and thoughts about retaliating against society’, they said.

Violent incidents targeting schoolchildren are not uncommon in China, which has seen a slew of deadly incidents over the past few years – usually involving knives.