Question: Where have you been when the explosion occurred?

Answer: I was in the lab with Prof. Shine. 

Question: Why were you in the lab with her at such a late hour?

Answer: I had to do extra credit because I failed my last exam.

Question: What caused the explosion?

Answer: She was testing some reactions. I was handing her some of the materials, but she was very impatient with me so she took two materials by herself. I guess she made a mistake, because the next thing I heard was a big - then I looked, and saw that she was knocked down, on the floor. I immediately called 911.