When she landed on the ground and miraculously managed to avoid hitting her head, Hermione was terribly confused. What just happened? She knew that she wasn't responsible. The incantation to conjure Fiendfyre had been on the tip of her tongue, not a reducto or whatever else spell was used to cause the explosion. Once she was satisfied that she was uninjured, she pulled herself up to her feet. She needed to be far away from the scene of the crime lest she be accused of being responsible.