Investigators say they've found a half dozen grenades among the military munitions in a suburban Phoenix home where a former Marine with ties to neo-Nazi groups shot four people and then took his own life.
An agent from the Bureau of Alcohol, Tobacco, Firearms and Explosives said Thursday that the agency is tracing the serial numbers of six 40 mm projectile grenades discovered in Jason Todd Ready's house.
Agent Tom Mangan says the explosives are strictly military-issue and should not be in a residence.
Officials from Luke Air Force Base have taken the grenades and destroyed them.
Warren Jones, manager of an Army surplus store in Phoenix, said that type of grenade is not available at any store.
"It clearly had to be acquired on the black market," Jones said. "It's not something they can just meet with somebody and purchase."
Jones said civilians with a special license can obtain them. However, there is usually paperwork required by ATF.
Gilbert police says the four others killed in Wednesday's shootings include 16-month-old Lily Lynn Mederos, 23-year-old Amber Nieve Mederos, 47 year-old Lisa Lynn Mederos and 24-year-old Jim Franklin Hiott.
Lisa Mederos is believed to be Ready's girlfriend.