(AP) — Adult siblings in Lincoln have been accused of brutally attacking a relative.

Lincoln police say 18-year-old Henrionce Cope and 20-year-old Sade Cope attacked 50-year-old Charles Riley Jr. on Sunday.

Officer Katie Flood said the siblings stabbed Riley 13 times in his head, arms and legs. They’re also accused of using a broken bottle and an iron in the attack.

Authorities say Riley is Henrionce Cope’s stepfather. It’s unclear what his relationship is to Sade Cope.

Riley was treated at a hospital. The siblings were arrested Monday without incident on suspicion of second-degree assault and using a weapon to commit a felony. Court records do not list attorneys.