A young Calgary boy charged with sexually assaulting three boys — aged six, four and two — made his first appearance in court Thursday.

The 13-year-old boy, who was originally reported to be 12, is charged with three counts of sexual assault and three counts of sexual interference. All the boys are residents of a foster home.

The accused had been staying at the home for quite some time, so police are now looking into the possibility of whether there are any more cases to investigate.

Calgary police arrested the boy after they were called to a southwest home for a report of a sexual assault around 10 p.m. MT Tuesday.

The 911 call was made by a witness who does not live at the home. There was one adult and the four children in the home at the time.

"This has been a horrifying, horrifying incident for the witnesses as well," said Det. Stephen Johnston. "They have suffered a lot from this."

The alleged assaults supposedly happened throughout the day on Tuesday. Police have been called to home before, but not for anything of this nature.

The accused will appear in court again Monday.