A car has slammed into a group of 16 mostly kindergarten children who were walking to school along a sidewalk in the lakeside city of Otsu in western Japan, leaving four seriously injured.

Shiga prefectural police say the accident occurred Wednesday morning after the compact car bumped into another passenger car at an intersection and veered off to the sidewalk. The 13 children were escorted by three teachers.

Police say the four children were unconscious, while the conditions of others in the group were not immediately known.

Kyodo News agency says police arrested the two drivers, ages 62 and 52, on suspicion of negligence.

In Japan children usually walk to school in groups.