While I am not licensed to practice law in Pennsylvania , the simple answer is "yes" even though fortunately no one was hurt! For more specic information may I strongly urge you to contact an attorney licensed in Pennsylvania.
Arson is a serious violent felony no matter where it's committed. What if you shot at some one and missed? Would your defense be no harm no foul. Better get the best defense lawyer you can find.
Arson (18 Pa.C.S. § 3301) is NOT always considered a "crime of violence" in Pennsylvania according to 42 Pa.C.S. § 9714(g). It depends on the subsection that you are charged with violating. An Arson conviction can result in a mandatory minimum sentence if it is considered a "crime of violence" and you possessed a firearm or a replica of a firearm. An Arson conviction counts as a "strike" against you if it qualifies as a "crime of violence" regardless if you possessed a gun. Arson can have an offense gravity score as high as ten, which can result in a sentence of incarceration in one of Pennsylvania's State Correctional Institutions.
Arson is a very serious charge. If you or a loved one is charged with Arson, contact a criminal defense attorney immediately.