PAHOA, Hawaii (AP) — Hawaii police and federal authorities are investigating after a man building homemade fireworks died following an explosion at his house.

Police on the Big Island said Tuesday the man was severely injured by an explosion early Saturday at his home in the Puna district. The man was flown to a Honolulu hospital, where he died, police said.

When police arrived at the home, the 35-year-old man was lying on the floor with a wound to his abdomen area. His wife and children were asleep but woke up because of the explosion shortly after 2 a.m.

The man had been making homemade fireworks at the time, police said.

Police found materials used to make fireworks, several guns and 214 marijuana plants.

The exact cause of the explosion is under investigation.