AKB48 holds the Guinness record for being the world’s largest pop group, with the current line-up standing at 140 names. Fans vote annually to choose new additions to the band from a 200-strong shortlist.
Twitter and other social networking sites were flooded with comments about the incident, many of them raising concerns about security checks. AKB48 members kept quiet about the case.
"Such an incident should never have happened. Even if they recover from their physical injuries, their emotional scars will never heal," former AKB48 member Erena Ono tweeted.
AKB48 management announced Monday it was canceling a concert at its main theater in Tokyo's Akihabara district, as well as several other events around Japan. Affiliates SKE48 in central Japan and NMB48 in Osaka also canceled or postponed events.