My daughter had a temper tantrum and said that she didn't want to live. Should I take this seriously?

She's 9 yrs old and very bright but extremely stubborn. For that reason, we don't get along too well; our personalities are very different. Anyway, during a meltdown, she said that she didn't want to live anymore because all she knows what to do is to whine (I tell her to quit whining because she does this too often, especially for her age). Then she punched her own arm a couple times out of frustration. Should I be concerned? I'm somewhat worried. Help!