The four Americans were killed when their unarmored vehicle was ambushed by Islamic militants. Sgt. Johnson's body was not recovered for almost two days after he was killed, according to this report.
In addition to his wife, who was pregnant with their third child, Johnson leaves behind his six year old daughter and his two year old son.
As the article linked above noted,
The US military held a return of remains ceremony when Johnson's body arrived at the Dover Air Force Base in Delaware Oct. 7, while president Donald Trump was playing golf with Sen. Lindsey Graham.I hope that the reports of Trump's comment are wrong. Or, if they're not wrong, the full context of his remarks comes out, to add some insight to what on the surface seems an incredibly insensitive remark.
In the meantime, in this Twitter thread, Brandon Friedman explains things from a veteran's perspective about the expectations one has when signing up for service.