In Lake County, Indiana, on May, 20 around 6:30 p.m. Police responded to a call from Lake of Four Seasons after a grenade, belonging to Bryan Niedert’s grandfather, went off in a home.

The 47-year-old and his two teens were affected by the explosion and were taken to the hospital. Niedert, who was found severely injured and unresponsive, died afterward. His 18-year-old daughter and 14-year-old son suffered shrapnel wounds.

Investigators were told that the family was going through his grandfather’s belongings at their home on Lakeshore Drive when they found the grenade. Police believed someone in the home had pulled the pin to the grenade, by accident, causing it to go off. Porter County sent its bomb squad to the scene to check if there were any other explosives in the home and to secure the area.

According to the FBI, some military veterans would bring back their explosives as souvenirs. Said souvenirs would sometimes be found by family members unexpectedly.