Can you be abused as a child by another child?

When I was at nursery (4 years old) some kids from the local primary school (about 10-11) used to look after us. But one boy used to take me to the toilets and give me oral or put my up him. I never spoke about this to anyone but I've always thought about it and wondered if it has affected my life as i've suffered many traumas and depression severly. Is that even possible?