Authorities say two people have been hacked to death and another nine injured by a man wielding a meat cleaver inside a Walmart store in China’s southern city of Shenzhen.

Police in the city’s Bao’an district said on Monday in an online statement that a 30-year-old unemployed man was detained as a suspect. They say the motive for the attack was not immediately known.

Firearms are largely unobtainable for ordinary Chinese, and such attacks are more often carried out with knives or homemade explosives. Sales of knives have faced stricter regulations following high-profile attacks, some of which have targeted schools.

Perpetrators of most past attacks have been described as being mentally ill or bearing grudges against society.