The commercial pilot was conducting a skydiving flight with a night aerial pyrotechnic display. According to the pilot and the lead jumper, who was also one of the airplane’s co-owners, a pyrotechnic box was installed on a step on the airplane’s left main landing gear assembly spring leg just before the flight. The pilot and the lead jumper reported that, after departure and as the airplane arrived at the planned jump area and altitude, the skydivers were given the go-ahead to jump, and one of the jumper’s activated the sparklers in the pyrotechnic box. Shortly thereafter, they heard an explosion and then saw damage to the bottom of the left wing with fuel pouring out of it. The left wing became engulfed in flames, and the skydivers successfully jumped out of the airplane.