MADRID (AP) — Police say three people have been killed in an explosion at a family-run firework factory in northwestern Spain.

A Civil Guard spokeswoman said the blast occurred late Thursday on the outskirts of the small town of Leiro. The dead included the factory's owner, his girlfriend and his son's girlfriend.

She said Friday that the son was injured in the blast.

The spokeswoman said initial investigations indicated the explosion was an accident. She spoke on condition of anonymity as police regulations do not allow her to be identified publicly.