Ibn Jurayj (may Allah have mercy on him) says: I said to Ata (may Allah have mercy on him): Allah Almighty says: "Do not kill game while you are in the state of ihram; and whoever of you kills it deliberately" [Surah al-Ma'idah: 95]. He said: I said: Whoever kills it by mistake, will a penalty be imposed on him? He said: Yes; by it the sacred limits of Allah are honoured, and the Sunnahs and practice have long been established on it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9859