The slashing incident Sunday at a major amusement park in western Tokyo has caught operators of other major theme parks off guard, prompting concerns that current security might not be enough to prevent similar incidents.

Around noon on Sunday at the large Cobalt Beach wave pool in Tokyo Summerland in the city of Akiruno, nine women aged 18 to 24 sustained minor wounds to their buttocks, abdomens and backs in an apparent attack using a razor blade-like object.

The police, after receiving a report from the amusement park's security staff at 1:20 p.m., began investigating, but the perpetrator remained at large as of Monday.