A mass stabbing around a school bus stop in Kawasaki that claimed the lives of two occurred over a period of less than 20 seconds, investigators said Wednesday.

Seventeen students of Caritas Elementary School, a private Catholic school in the city near Tokyo, and two parents were attacked Tuesday, most while waiting for the school bus.

Police searched the suspect's home in Kawasaki on Wednesday looking for clues about the attack, in which a schoolgirl and the father of an unharmed pupil were killed.