XI'AN, March 17 -- One person was killed and another was seriously injured in a knife attack in Chunhua County in northwest China's Shaanxi Province on Tuesday afternoon, local authorities said.

According to police, a 50-year-old local farmer killed his wife's sister and injured his brother-in-law's wife with a knife. The injured woman is in critical condition.

The attacker committed suicide by poisoning after the attack.

Police are investigating the case.