ROCHESTER — Rochester police are investigating what may have motivated a man to stab and critically injure the 12-year-old daughter of an acquaintance.

The 31-year-old man was arrested Tuesday afternoon, about 12 hours after the girl was stabbed in the chest at her home. Police said the girl was in critical condition at St Marys Hospital.

Authorities said the man knew the girl’s mother, who suffered minor injuries when struggling with the man.

Rochester police don’t know how the man got into the victims’ apartment.