LAKES OF THE FOUR SEASONS, Ind. (AP) — A hand grenade found as a family went through an older relative’s belongings exploded, killing an Indiana man and injuring his two teenage children, police said.

The explosion fatally injured the 47-year-old man Saturday evening at the home in the community of Lakes of the Four Seasons in northwestern Indiana, according to the Lake County Sheriff’s Department. His two children, a 14-year-old boy and 18-year-old girl, were taken to a hospital with shrapnel wounds.

Sheriff Oscar Martinez said investigators were trying to determine what caused the grenade to explode in the home about 30 miles (50 kilometers) southeast of Chicago.

Authorities didn’t immediately release any additional information about the grenade or why the relative had it.