Police say a man wielding a knife has injured four people in the third such rampage in South Korea in less than a week.

A police officer says the man attacked his victims Wednesday in Seoul's Yeouido area. He says a 30-year-old surnamed Kim was arrested and none of the injuries was life-threatening. Another officer said two victims worked with Kim previously.

Both officers declined to be named or provide more details because the investigation has just begun. They say the man's motive was unclear.

Another man was arrested after cutting or stabbing eight people Saturday at a subway station just outside of Seoul. And another attacker killed one person and injured four Tuesday in a city south of Seoul. Such rampages have been rare in South Korea.