JOPLIN, Mo. (AP) — Authorities have charged a Missouri man with shooting and critically wounding his son and killing his son’s girlfriend after he was told he couldn’t see his grandchildren again.

The Joplin Globe reports that 60-year-old Rickey Lamb, of rural Joplin, is jailed on $500,000 bond on charges of first-degree murder, first-degree domestic assault and two counts of armed criminal action.

He told deputies that his son, 35-year-old Chris Lamb, fired first Monday morning. Court records say he also told deputies that he fatally shot 32-year-old Sarah Tyminski when she picked up a shotgun. He said he had being taking care of the couple’s children for about a year when the custody dispute arose. A witness disputed his account of who fired first.

No attorney is listed for him in online court records.