User blog comment:Roranoa zoro/Latest Chapter Discussion/@comment-24769684-20141002212747/@comment-96.42.191.61-20141003001207

The parents were killed while he was talking to his sister and then when he heard the other ruckus outside he ran there and found all the kids and nun were killed. At the time he was seeing that the hospital/house was burned. Essentially they were trying to finish wiping out the entire city at the time.