At least seven students have been stabbed to death and 12 injured in a knife attack outside a school in northern China, BBC reported quoting officials.

The knife-wielding man attacked the students near a secondary school in Mizhi County in Shaanxi province as they were heading home for the day, officials were quoted as saying.

A suspect is said to be in police custody.

Photos on social media showed several young students lying on the floor, surrounded by shocked onlookers.

A local government statement said the attack happened at Mizhi County Number Three secondary school, at around 18:10 local time (10:10 GMT).

Their exact ages have not been given, but reports suggest they may be middle school children, which would make them aged 12 to 15, reported BBC.

Knife attacks over the years have sporadically taken place in China.

On February 11, a woman was killed and 12 other people were injured after a man carried out a knife attack in a mall in a busy shopping district in Beijing.

Three men and 10 women were sent to hospital after the attack and one woman died of her injuries, police had said.

Two days later, on February 13, eight people were killed in a knife attack on a crowd in China’s restive Xinjiang region, including three assailants who were gunned down by police.