A gunman who killed five girls in an attack on a Pennsylvania Amish school told his wife he had molested two young members of his family 20 years ago.

Charles Carl Roberts, 32, made the claim in a phone call to his wife just before he started shooting the girls. He also made references to an incident 20 years ago in suicide notes and said he had been haunted by dreams of repeating his actions.

Police said it was possible his attack on the girls was sexually motivated. Five girls remain in hospital – one is critical and one is in serious condition. Three are described as stable. However, there was no evidence that any of the girls at the school had been sexually abused, though Roberts had been equipped with a “restraint kit” and two tubes of lubricant gel, which he could have been planning to use in a sexual assault.

All of the victims were young girls aged six to 13 and that all of the older women and males in the classroom had been made to leave. The members of Roberts’ family, including two who were aged between three and five years old 20 years ago, had been interviewed following his abuse confession, but all said they had no knowledge of any such molestation occurring.