It is written in a
Harry Potter wiki:
Fred, along with his family and friends, returned to Hogwarts in the spring to participate in the final battle. He and George were assigned to defend the castle's secret passages by Kingsley Shacklebolt. When the Death Eaters forced their way inside, Fred fought next to his brother Percy, who had recently been reconciled with the family and combatted his former boss, Imperiused Minister for Magic Pius Thicknesse. Fred was killed in an explosion possibly caused by Augustus Rookwood. Here is Augustus Rookwood's picture
exactly, Percy yelled Rookwood when Fred died , but i was never sure if in fact he killed Fred or he was just looking for a death eater to kill ,thanks for awnsering
