Can a 12 year old get depressed?

For the past 4 months I have seen a big change in my daughter ! Shes seems to be depressed. Like can 12 year olds actually be depressed ? What signs should I look for ? I am really worried about her !! Should I take her to see a doctor? Counsellor? I'm so stressed about this .. and when I try to talk to her about this . She snaps at me !! :(