Toddlers behavior problem

My 15 months old toddler is currently attending infant care . Today i was informed that she scratched her friend's face leaving four finger marks . Is there any way that i can diciplain or teach ? So worried that this issue will come again in future . Teacher say is becus her frien snatch her toy or vice versa. She will always get angry when someone take her toy . And will hurt the other party. How to stop this ?